diff --git a/packages/serialise/serialise.pony b/packages/serialise/serialise.pony
index 66e71fc535..d169ba7ce8 100644
--- a/packages/serialise/serialise.pony
+++ b/packages/serialise/serialise.pony
@@ -15,16 +15,18 @@ invariants. However, if only "trusted" data (i.e. data produced by Pony
 serialisation from the same binary) is deserialised, it will always maintain a
 well-formed heap and all object invariants.
 
-Note that serialised data is not usable between different Pony binaries. This is
-due to the use of type identifiers rather than a heavy-weight self-describing
-serialisation schema. This also means it isn't safe to deserialise something
-serialised by the same program compiled for a different platform.
+Note that serialised data can be used between binaries compiled with the same
+version of the pony compiler. Cross binary serialisation will only work for
+binaries of the same bit width (32 bit vs 64 bit), data model (ilp32, lp64, or
+llp64), and endianness (big endian or little endian) but is not limited to a
+single platform (for example: one can mix and match x86_64 linux and aarch64
+linux because they have the same bitwidth, data model, and endianness).
 
 The [Serialise.signature](serialise-Serialise.md#signature) method is provided
 for the purposes of comparing communicating Pony binaries to determine if they
-are the same. Confirming this before deserialising data can help mitigate the
-risk of accidental serialisation across different Pony binaries, but does not on
-its own address the security issues of accepting data from untrusted sources.
+are compatible. Confirming this before deserialising data can help mitigate the
+risk of accidental serialisation across incompatible Pony binaries, but does not
+on its own address the security issues of accepting data from untrusted sources.
 """
 
 use @"internal.signature"[Array[U8] val]()
diff --git a/src/libponyc/ast/ast.c b/src/libponyc/ast/ast.c
index d0774aea49..31d13660d5 100644
--- a/src/libponyc/ast/ast.c
+++ b/src/libponyc/ast/ast.c
@@ -2013,6 +2013,7 @@ static pony_type_t ast_signature_pony =
   sizeof(ast_signature_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   ast_signature_serialise_trace,
@@ -2092,6 +2093,7 @@ static pony_type_t ast_nominal_pkg_id_signature_pony =
   sizeof(ast_signature_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   ast_nominal_pkg_id_signature_serialise_trace,
@@ -2355,6 +2357,7 @@ static pony_type_t ast_pony =
   sizeof(ast_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   ast_serialise_trace,
diff --git a/src/libponyc/ast/source.c b/src/libponyc/ast/source.c
index 1e01cff87e..be0cbd926f 100644
--- a/src/libponyc/ast/source.c
+++ b/src/libponyc/ast/source.c
@@ -114,6 +114,7 @@ static pony_type_t source_pony =
   sizeof(source_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   source_serialise_trace,
diff --git a/src/libponyc/ast/stringtab.c b/src/libponyc/ast/stringtab.c
index 9a83b8efde..7b1ded094c 100644
--- a/src/libponyc/ast/stringtab.c
+++ b/src/libponyc/ast/stringtab.c
@@ -134,6 +134,7 @@ static __pony_thread_local struct _pony_type_t string_pony =
   0,
   0,
   0,
+  0,
   NULL,
   NULL,
   NULL,
@@ -220,6 +221,7 @@ static pony_type_t strlist_pony =
   sizeof(strlist_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   strlist_serialise_trace,
diff --git a/src/libponyc/ast/symtab.c b/src/libponyc/ast/symtab.c
index 09b9e67b99..b972254e4f 100644
--- a/src/libponyc/ast/symtab.c
+++ b/src/libponyc/ast/symtab.c
@@ -389,6 +389,7 @@ static pony_type_t symbol_pony =
   sizeof(symbol_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   symbol_serialise_trace,
diff --git a/src/libponyc/ast/token.c b/src/libponyc/ast/token.c
index 14ebb96be0..fb876e9492 100644
--- a/src/libponyc/ast/token.c
+++ b/src/libponyc/ast/token.c
@@ -404,6 +404,7 @@ static pony_type_t token_signature_pony =
   sizeof(token_signature_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   token_signature_serialise_trace,
@@ -458,6 +459,7 @@ static pony_type_t token_docstring_signature_pony =
   sizeof(token_signature_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   token_docstring_signature_serialise_trace,
@@ -546,6 +548,7 @@ static pony_type_t token_pony =
   sizeof(token_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   token_serialise_trace,
diff --git a/src/libponyc/codegen/codegen.c b/src/libponyc/codegen/codegen.c
index a4536e70f7..a0727e13a3 100644
--- a/src/libponyc/codegen/codegen.c
+++ b/src/libponyc/codegen/codegen.c
@@ -15,6 +15,7 @@
 #include "../../libponyrt/mem/pool.h"
 #include "ponyassert.h"
 
+#include <blake2.h>
 #include <platform.h>
 #include <llvm-c/DebugInfo.h>
 #include <llvm-c/Initialization.h>
@@ -202,6 +203,13 @@ static void init_runtime(compile_t* c)
   c->msg_type = LLVMStructCreateNamed(c->context, "__message");
   LLVMStructSetBody(c->msg_type, params, 2, false);
 
+  // descriptor_offset_lookup
+  // uint32_t (*)(size_t)
+  params[0] = target_is_ilp32(c->opt->triple) ? c->i32 : c->i64;
+  c->descriptor_offset_lookup_type = LLVMFunctionType(c->i32, params, 1, false);
+  c->descriptor_offset_lookup_fn =
+    LLVMPointerType(c->descriptor_offset_lookup_type, 0);
+
   // trace
   // void (*)(i8*, __object*)
   params[0] = c->ptr;
@@ -856,6 +864,21 @@ bool codegen_pass_init(pass_opt_t* opt)
   else
     opt->cpu = LLVMGetHostCPUName();
 
+  opt->serialise_id_hash_key = (unsigned char*)ponyint_pool_alloc_size(16);
+
+  const char* version = "pony-" PONY_VERSION;
+  const char* data_model = target_is_ilp32(opt->triple) ? "ilp32" : (target_is_lp64(opt->triple) ? "lp64" : (target_is_llp64(opt->triple) ? "llp64" : "unknown"));
+  const char* endian = target_is_bigendian(opt->triple) ? "be" : "le";
+
+  printbuf_t* target_version_buf = printbuf_new();
+  printbuf(target_version_buf, "%s-%s-%s", version, data_model, endian);
+
+  int status = blake2b(opt->serialise_id_hash_key, 16, target_version_buf->m, target_version_buf->offset, NULL, 0);
+  (void)status;
+  pony_assert(status == 0);
+
+  printbuf_free(target_version_buf);
+
   return true;
 }
 
@@ -872,6 +895,9 @@ void codegen_pass_cleanup(pass_opt_t* opt)
   opt->triple = NULL;
   opt->cpu = NULL;
   opt->features = NULL;
+
+  ponyint_pool_free_size(16, opt->serialise_id_hash_key);
+  opt->serialise_id_hash_key = NULL;
 }
 
 bool codegen(ast_t* program, pass_opt_t* opt)
diff --git a/src/libponyc/codegen/codegen.h b/src/libponyc/codegen/codegen.h
index 822ea3982b..c95d943f05 100644
--- a/src/libponyc/codegen/codegen.h
+++ b/src/libponyc/codegen/codegen.h
@@ -172,6 +172,7 @@ typedef struct compile_t
   LLVMValueRef primitives_init;
   LLVMValueRef primitives_final;
   LLVMValueRef desc_table;
+  LLVMValueRef desc_table_offset_lookup_fn;
   LLVMValueRef numeric_sizes;
 
   LLVMTypeRef void_type;
@@ -187,6 +188,8 @@ typedef struct compile_t
 
   LLVMTypeRef ptr;
   LLVMTypeRef descriptor_type;
+  LLVMTypeRef descriptor_offset_lookup_type;
+  LLVMTypeRef descriptor_offset_lookup_fn;
   LLVMTypeRef field_descriptor;
   LLVMTypeRef object_type;
   LLVMTypeRef msg_type;
diff --git a/src/libponyc/codegen/gendesc.c b/src/libponyc/codegen/gendesc.c
index b1444d2a4b..f9455f4c52 100644
--- a/src/libponyc/codegen/gendesc.c
+++ b/src/libponyc/codegen/gendesc.c
@@ -12,24 +12,25 @@
 
 #define DESC_ID 0
 #define DESC_SIZE 1
-#define DESC_FIELD_COUNT 2
-#define DESC_FIELD_OFFSET 3
-#define DESC_INSTANCE 4
-#define DESC_TRACE 5
-#define DESC_SERIALISE_TRACE 6
-#define DESC_SERIALISE 7
-#define DESC_DESERIALISE 8
-#define DESC_CUSTOM_SERIALISE_SPACE 9
-#define DESC_CUSTOM_DESERIALISE 10
-#define DESC_DISPATCH 11
-#define DESC_FINALISE 12
-#define DESC_EVENT_NOTIFY 13
-#define DESC_MIGHT_REFERENCE_ACTOR 14
-#define DESC_TRAITS 15
-#define DESC_FIELDS 16
-#define DESC_VTABLE 17
-
-#define DESC_LENGTH 18
+#define DESC_SERIALISEID 2
+#define DESC_FIELD_COUNT 3
+#define DESC_FIELD_OFFSET 4
+#define DESC_INSTANCE 5
+#define DESC_TRACE 6
+#define DESC_SERIALISE_TRACE 7
+#define DESC_SERIALISE 8
+#define DESC_DESERIALISE 9
+#define DESC_CUSTOM_SERIALISE_SPACE 10
+#define DESC_CUSTOM_DESERIALISE 11
+#define DESC_DISPATCH 12
+#define DESC_FINALISE 13
+#define DESC_EVENT_NOTIFY 14
+#define DESC_MIGHT_REFERENCE_ACTOR 15
+#define DESC_TRAITS 16
+#define DESC_FIELDS 17
+#define DESC_VTABLE 18
+
+#define DESC_LENGTH 19
 
 static LLVMValueRef make_unbox_function(compile_t* c, reach_type_t* t,
   reach_method_t* m)
@@ -330,6 +331,7 @@ void gendesc_basetype(compile_t* c, LLVMTypeRef desc_type)
 
   params[DESC_ID] = c->i32;
   params[DESC_SIZE] = c->i32;
+  params[DESC_SERIALISEID] = target_is_ilp32(c->opt->triple) ? c->i32 : c->i64;
   params[DESC_FIELD_COUNT] = c->i32;
   params[DESC_FIELD_OFFSET] = c->i32;
   params[DESC_INSTANCE] = c->ptr;
@@ -377,6 +379,7 @@ void gendesc_type(compile_t* c, reach_type_t* t)
 
   params[DESC_ID] = c->i32;
   params[DESC_SIZE] = c->i32;
+  params[DESC_SERIALISEID] = target_is_ilp32(c->opt->triple) ? c->i32 : c->i64;
   params[DESC_FIELD_COUNT] = c->i32;
   params[DESC_FIELD_OFFSET] = c->i32;
   params[DESC_INSTANCE] = c->ptr;
@@ -414,6 +417,7 @@ void gendesc_init(compile_t* c, reach_type_t* t)
   LLVMValueRef args[DESC_LENGTH];
   args[DESC_ID] = LLVMConstInt(c->i32, t->type_id, false);
   args[DESC_SIZE] = LLVMConstInt(c->i32, c_t->abi_size, false);
+  args[DESC_SERIALISEID] = LLVMConstInt(target_is_ilp32(c->opt->triple) ? c->i32 : c->i64, t->serialise_id, false);
   args[DESC_FIELD_COUNT] = make_field_count(c, t);
   args[DESC_FIELD_OFFSET] = make_field_offset(c, t);
   args[DESC_INSTANCE] = make_desc_ptr(c, c_t->instance);
@@ -478,6 +482,58 @@ void gendesc_table(compile_t* c)
   ponyint_pool_free_size(size, args);
 }
 
+void gendesc_table_lookup(compile_t* c)
+{
+  reach_type_t* t;
+  size_t i = HASHMAP_BEGIN;
+
+  LLVMValueRef desc_lkp_fn = codegen_addfun(c, "__DescOffsetLookupFn",
+    c->descriptor_offset_lookup_type, false);
+  codegen_startfun(c, desc_lkp_fn, NULL, NULL, NULL, false);
+  LLVMSetFunctionCallConv(desc_lkp_fn, LLVMCCallConv);
+  LLVMSetLinkage(desc_lkp_fn, LLVMExternalLinkage);
+
+  LLVMBasicBlockRef unreachable = codegen_block(c, "unreachable");
+
+  // Read the serialise ID.
+  LLVMValueRef serialise_id = LLVMGetParam(desc_lkp_fn, 0);
+
+  // switch based on serialise_id
+  LLVMValueRef serialise_switch = LLVMBuildSwitch(c->builder, serialise_id, unreachable, 0);
+
+  // the default case is unreachable unless something major has gone wrong
+  LLVMPositionBuilderAtEnd(c->builder, unreachable);
+
+  LLVMValueRef ret = LLVMConstInt(c->i32, (uint32_t)-1, false);
+  LLVMBuildRet(c->builder, ret);
+
+  while((t = reach_types_next(&c->reach->types, &i)) != NULL)
+  {
+    if(t->is_trait || (t->underlying == TK_STRUCT))
+      continue;
+
+    pony_assert(t->serialise_id != (uint64_t)-1);
+
+    LLVMBasicBlockRef type_block = codegen_block(c,
+      genname_type_with_id(t->name, t->serialise_id));
+
+    LLVMAddCase(serialise_switch, LLVMConstInt(target_is_ilp32(c->opt->triple) ? c->i32 : c->i64, t->serialise_id, false),
+      type_block);
+
+    LLVMPositionBuilderAtEnd(c->builder, type_block);
+
+    ret = LLVMConstInt(c->i32, t->type_id, false);
+    LLVMBuildRet(c->builder, ret);
+  }
+
+  // Mark the default case as unreachable.
+  LLVMPositionBuilderAtEnd(c->builder, unreachable);
+
+  codegen_finishfun(c);
+
+  c->desc_table_offset_lookup_fn = make_desc_ptr(c, desc_lkp_fn);
+}
+
 static LLVMValueRef desc_field(compile_t* c, LLVMValueRef desc, int index)
 {
   LLVMTypeRef field_type = LLVMStructGetTypeAtIndex(c->descriptor_type, index);
diff --git a/src/libponyc/codegen/gendesc.h b/src/libponyc/codegen/gendesc.h
index 97c76aea27..cd8f7a90a7 100644
--- a/src/libponyc/codegen/gendesc.h
+++ b/src/libponyc/codegen/gendesc.h
@@ -14,6 +14,8 @@ void gendesc_init(compile_t* c, reach_type_t* t);
 
 void gendesc_table(compile_t* c);
 
+void gendesc_table_lookup(compile_t* c);
+
 LLVMValueRef gendesc_fetch(compile_t* c, LLVMValueRef object);
 
 LLVMValueRef gendesc_typeid(compile_t* c, LLVMValueRef desc);
diff --git a/src/libponyc/codegen/genexe.c b/src/libponyc/codegen/genexe.c
index 9ae3ff1679..832c83969a 100644
--- a/src/libponyc/codegen/genexe.c
+++ b/src/libponyc/codegen/genexe.c
@@ -52,14 +52,16 @@ static LLVMValueRef make_lang_features_init(compile_t* c)
     boolean = c->i8;
 
   uint32_t desc_table_size = reach_max_type_id(c->reach);
+  LLVMValueRef desc_table_lookup_fn = c->desc_table_offset_lookup_fn;
 
-  LLVMTypeRef f_params[4];
+  LLVMTypeRef f_params[5];
   f_params[0] = boolean;
   f_params[1] = boolean;
   f_params[2] = c->ptr;
   f_params[3] = c->intptr;
+  f_params[4] = c->descriptor_offset_lookup_fn;
 
-  LLVMTypeRef lfi_type = LLVMStructTypeInContext(c->context, f_params, 4,
+  LLVMTypeRef lfi_type = LLVMStructTypeInContext(c->context, f_params, 5,
     false);
 
   LLVMBasicBlockRef this_block = LLVMGetInsertBlock(c->builder);
@@ -89,6 +91,10 @@ static LLVMValueRef make_lang_features_init(compile_t* c)
   LLVMBuildStore(c->builder, LLVMConstInt(c->intptr, desc_table_size, false),
     field);
 
+  field = LLVMBuildStructGEP2(c->builder, lfi_type, lfi_object, 4, "");
+  LLVMBuildStore(c->builder, LLVMBuildBitCast(c->builder, desc_table_lookup_fn,
+    c->descriptor_offset_lookup_fn, ""), field);
+
   return lfi_object;
 }
 
diff --git a/src/libponyc/codegen/genname.c b/src/libponyc/codegen/genname.c
index a481f31dca..cab07cf70a 100644
--- a/src/libponyc/codegen/genname.c
+++ b/src/libponyc/codegen/genname.c
@@ -199,3 +199,10 @@ const char* genname_program_fn(const char* program, const char* name)
 {
   return stringtab_two(program, name);
 }
+
+const char* genname_type_with_id(const char* type, uint64_t type_id)
+{
+  printbuf_t* buf = printbuf_new();
+  printbuf(buf, "%s_%" PRIu64, type, type_id);
+  return stringtab_buf(buf);
+}
diff --git a/src/libponyc/codegen/genname.h b/src/libponyc/codegen/genname.h
index 13d39ee334..ce160524b0 100644
--- a/src/libponyc/codegen/genname.h
+++ b/src/libponyc/codegen/genname.h
@@ -42,6 +42,8 @@ const char* genname_unsafe(const char* name);
 
 const char* genname_program_fn(const char* program, const char* name);
 
+const char* genname_type_with_id(const char* type, uint64_t type_id);
+
 PONY_EXTERN_C_END
 
 #endif
diff --git a/src/libponyc/codegen/genprim.c b/src/libponyc/codegen/genprim.c
index d5fb517ec2..4da0b2b73b 100644
--- a/src/libponyc/codegen/genprim.c
+++ b/src/libponyc/codegen/genprim.c
@@ -776,7 +776,7 @@ void genprim_array_serialise(compile_t* c, reach_type_t* t)
   LLVMValueRef offset_addr = LLVMBuildInBoundsGEP2(c->builder, c->i8, addr,
     &offset, 1, "");
 
-  genserialise_typeid(c, t, offset_addr);
+  genserialise_serialiseid(c, t, offset_addr);
 
   // Don't serialise our contents if we are opaque.
   LLVMBasicBlockRef body_block = codegen_block(c, "body");
@@ -890,7 +890,7 @@ void genprim_array_deserialise(compile_t* c, reach_type_t* t)
 
   LLVMValueRef ctx = LLVMGetParam(c_t->deserialise_fn, 0);
   LLVMValueRef object = LLVMGetParam(c_t->deserialise_fn, 1);
-  gendeserialise_typeid(c, c_t, object);
+  gendeserialise_serialiseid(c, c_t, object);
 
   // Deserialise the array contents.
   LLVMValueRef alloc = field_value(c, c_t->structure, object, 2);
@@ -1010,7 +1010,7 @@ void genprim_string_serialise(compile_t* c, reach_type_t* t)
   LLVMValueRef offset_addr = LLVMBuildInBoundsGEP2(c->builder, c->i8, addr,
     &offset, 1, "");
 
-  genserialise_typeid(c, t, offset_addr);
+  genserialise_serialiseid(c, t, offset_addr);
 
   // Don't serialise our contents if we are opaque.
   LLVMBasicBlockRef body_block = codegen_block(c, "body");
@@ -1069,7 +1069,7 @@ void genprim_string_deserialise(compile_t* c, reach_type_t* t)
   LLVMValueRef ctx = LLVMGetParam(c_t->deserialise_fn, 0);
   LLVMValueRef object = LLVMGetParam(c_t->deserialise_fn, 1);
 
-  gendeserialise_typeid(c, c_t, object);
+  gendeserialise_serialiseid(c, c_t, object);
 
   // Deserialise the string contents.
   LLVMValueRef alloc = field_value(c, c_t->structure, object, 2);
diff --git a/src/libponyc/codegen/genserialise.c b/src/libponyc/codegen/genserialise.c
index e641dcd67a..f2abaf5f66 100644
--- a/src/libponyc/codegen/genserialise.c
+++ b/src/libponyc/codegen/genserialise.c
@@ -3,6 +3,7 @@
 #include "gendesc.h"
 #include "genfun.h"
 #include "genname.h"
+#include "genopt.h"
 #include "genprim.h"
 #include "ponyassert.h"
 #include "../../libponyrt/mem/pool.h"
@@ -19,7 +20,7 @@ static void serialise(compile_t* c, reach_type_t* t, LLVMValueRef ctx,
   {
     case TK_PRIMITIVE:
     {
-      genserialise_typeid(c, t, offset);
+      genserialise_serialiseid(c, t, offset);
 
       if(c_t->primitive != NULL)
       {
@@ -37,7 +38,7 @@ static void serialise(compile_t* c, reach_type_t* t, LLVMValueRef ctx,
 
     case TK_CLASS:
     {
-      genserialise_typeid(c, t, offset);
+      genserialise_serialiseid(c, t, offset);
       extra++;
       break;
     }
@@ -45,7 +46,7 @@ static void serialise(compile_t* c, reach_type_t* t, LLVMValueRef ctx,
     case TK_ACTOR:
     {
       // Skip the actor pad.
-      genserialise_typeid(c, t, offset);
+      genserialise_serialiseid(c, t, offset);
       extra += 2;
       break;
     }
@@ -54,7 +55,7 @@ static void serialise(compile_t* c, reach_type_t* t, LLVMValueRef ctx,
     {
       if(!is_bare_tuple)
       {
-        genserialise_typeid(c, t, offset);
+        genserialise_serialiseid(c, t, offset);
         object = LLVMBuildStructGEP2(c->builder, c_t->structure, object, 1, "");
         LLVMValueRef size = LLVMConstInt(c->intptr,
           LLVMOffsetOfElement(c->target_data, structure, 1), false);
@@ -103,10 +104,10 @@ static void serialise(compile_t* c, reach_type_t* t, LLVMValueRef ctx,
   }
 }
 
-void genserialise_typeid(compile_t* c, reach_type_t* t, LLVMValueRef offset)
+void genserialise_serialiseid(compile_t* c, reach_type_t* t, LLVMValueRef offset)
 {
-  // Write the type id instead of the descriptor.
-  LLVMValueRef value = LLVMConstInt(c->intptr, t->type_id, false);
+  // Write the serialise id instead of the descriptor.
+  LLVMValueRef value = LLVMConstInt(target_is_ilp32(c->opt->triple) ? c->i32 : c->i64, t->serialise_id, false);
   LLVMBuildStore(c->builder, value, offset);
 }
 
@@ -136,7 +137,7 @@ static void serialise_bare_interface(compile_t* c, reach_type_t* t,
     LLVMValueRef test = LLVMBuildICmp(c->builder, LLVMIntEQ, obj,
       ((compile_type_t*)sub->c_type)->instance, "");
     LLVMBuildCondBr(c->builder, test, post_block, next_block);
-    LLVMValueRef value = LLVMConstInt(c->intptr, sub->type_id, false);
+    LLVMValueRef value = LLVMConstInt(target_is_ilp32(c->opt->triple) ? c->i32 : c->i64, sub->serialise_id, false);
     LLVMAddIncoming(phi, &value, &current_block, 1);
     LLVMPositionBuilderAtEnd(c->builder, next_block);
     sub = next;
@@ -145,7 +146,7 @@ static void serialise_bare_interface(compile_t* c, reach_type_t* t,
   }
 
   LLVMBuildBr(c->builder, post_block);
-  LLVMValueRef value = LLVMConstInt(c->intptr, sub->type_id, false);
+  LLVMValueRef value = LLVMConstInt(target_is_ilp32(c->opt->triple) ? c->i32 : c->i64, sub->serialise_id, false);
   LLVMAddIncoming(phi, &value, &current_block, 1);
 
   LLVMMoveBasicBlockAfter(post_block, current_block);
@@ -168,12 +169,12 @@ void genserialise_element(compile_t* c, reach_type_t* t, bool embed,
     LLVMValueRef value = LLVMBuildLoad2(c->builder, c_t->mem_type, ptr, "");
     LLVMBuildStore(c->builder, value, offset);
   } else if(t->bare_method != NULL) {
-    // Bare object, either write the type id directly if it is a concrete object
-    // or compute the type id based on the object value and write it if it isn't.
+    // Bare object, either write the serialise_id id directly if it is a concrete object
+    // or compute the serialise_id id based on the object value and write it if it isn't.
     switch(t->underlying)
     {
       case TK_PRIMITIVE:
-        genserialise_typeid(c, t, offset);
+        genserialise_serialiseid(c, t, offset);
         break;
 
       case TK_INTERFACE:
@@ -237,7 +238,7 @@ static void deserialise(compile_t* c, reach_type_t* t, LLVMValueRef ctx,
     case TK_PRIMITIVE:
     case TK_CLASS:
     {
-      gendeserialise_typeid(c, c_t, object);
+      gendeserialise_serialiseid(c, c_t, object);
       extra++;
       break;
     }
@@ -245,7 +246,7 @@ static void deserialise(compile_t* c, reach_type_t* t, LLVMValueRef ctx,
     case TK_ACTOR:
     {
       // Skip the actor pad.
-      gendeserialise_typeid(c, c_t, object);
+      gendeserialise_serialiseid(c, c_t, object);
       extra += 2;
       break;
     }
@@ -254,7 +255,7 @@ static void deserialise(compile_t* c, reach_type_t* t, LLVMValueRef ctx,
     {
       if(!is_bare_tuple)
       {
-        gendeserialise_typeid(c, c_t, object);
+        gendeserialise_serialiseid(c, c_t, object);
         object = LLVMBuildStructGEP2(c->builder, c_t->structure, object, 1, "");
       }
 
@@ -274,9 +275,9 @@ static void deserialise(compile_t* c, reach_type_t* t, LLVMValueRef ctx,
   }
 }
 
-void gendeserialise_typeid(compile_t* c, compile_type_t* t, LLVMValueRef object)
+void gendeserialise_serialiseid(compile_t* c, compile_type_t* t, LLVMValueRef object)
 {
-  // Write the descriptor instead of the type id.
+  // Write the descriptor instead of the serialiseid id.
   LLVMValueRef desc_ptr = LLVMBuildStructGEP2(c->builder, t->structure, object,
     0, "");
   LLVMBuildStore(c->builder, t->desc, desc_ptr);
diff --git a/src/libponyc/codegen/genserialise.h b/src/libponyc/codegen/genserialise.h
index 45743be46e..92d4d9803f 100644
--- a/src/libponyc/codegen/genserialise.h
+++ b/src/libponyc/codegen/genserialise.h
@@ -11,9 +11,9 @@ typedef struct compile_type_t compile_type_t;
 void genserialise_element(compile_t* c, reach_type_t* t, bool embed,
   LLVMValueRef ctx, LLVMValueRef ptr, LLVMValueRef offset);
 
-void genserialise_typeid(compile_t* c, reach_type_t* t, LLVMValueRef offset);
+void genserialise_serialiseid(compile_t* c, reach_type_t* t, LLVMValueRef offset);
 
-void gendeserialise_typeid(compile_t* c, compile_type_t* t, LLVMValueRef offset);
+void gendeserialise_serialiseid(compile_t* c, compile_type_t* t, LLVMValueRef offset);
 
 void gendeserialise_element(compile_t* c, reach_type_t* t, bool embed,
   LLVMValueRef ctx, LLVMValueRef ptr);
diff --git a/src/libponyc/codegen/gentype.c b/src/libponyc/codegen/gentype.c
index 049947c0aa..6c93bb7947 100644
--- a/src/libponyc/codegen/gentype.c
+++ b/src/libponyc/codegen/gentype.c
@@ -744,6 +744,7 @@ bool gentypes(compile_t* c)
   }
 
   gendesc_table(c);
+  gendesc_table_lookup(c);
 
   c->numeric_sizes = gen_numeric_size_table(c);
 
diff --git a/src/libponyc/pass/pass.h b/src/libponyc/pass/pass.h
index c3356dcab6..5a52ced437 100644
--- a/src/libponyc/pass/pass.h
+++ b/src/libponyc/pass/pass.h
@@ -313,6 +313,7 @@ typedef struct pass_opt_t
   char* abi;
   char* cpu;
   char* features;
+  unsigned char* serialise_id_hash_key;
 
   typecheck_t check;
 
diff --git a/src/libponyc/pkg/package.c b/src/libponyc/pkg/package.c
index 531f707987..2ee105ac05 100644
--- a/src/libponyc/pkg/package.c
+++ b/src/libponyc/pkg/package.c
@@ -1430,6 +1430,7 @@ static pony_type_t package_dep_signature_pony =
   sizeof(package_signature_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   package_dep_signature_serialise_trace,
@@ -1459,6 +1460,7 @@ static pony_type_t package_signature_pony =
   sizeof(package_signature_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   package_signature_serialise_trace,
@@ -1537,6 +1539,7 @@ static pony_type_t package_group_dep_signature_pony =
   sizeof(const char*),
   0,
   0,
+  0,
   NULL,
   NULL,
   package_group_dep_signature_serialise_trace,
@@ -1566,6 +1569,7 @@ static pony_type_t package_group_signature_pony =
   sizeof(const char*),
   0,
   0,
+  0,
   NULL,
   NULL,
   package_group_signature_serialise_trace,
@@ -1715,6 +1719,7 @@ static pony_type_t package_pony =
   sizeof(package_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   package_serialise_trace,
@@ -1788,6 +1793,7 @@ static pony_type_t package_group_pony =
   sizeof(package_group_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   package_group_serialise_trace,
diff --git a/src/libponyc/pkg/program.c b/src/libponyc/pkg/program.c
index a27095a91b..fb60c2979b 100644
--- a/src/libponyc/pkg/program.c
+++ b/src/libponyc/pkg/program.c
@@ -425,6 +425,7 @@ static pony_type_t program_pony =
   sizeof(program_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   program_serialise_trace,
diff --git a/src/libponyc/reach/reach.c b/src/libponyc/reach/reach.c
index ea2e77ae7d..8e3760595f 100644
--- a/src/libponyc/reach/reach.c
+++ b/src/libponyc/reach/reach.c
@@ -2,6 +2,7 @@
 #include "subtype.h"
 #include "../ast/astbuild.h"
 #include "../codegen/genname.h"
+#include "../codegen/genopt.h"
 #include "../pass/expr.h"
 #include "../type/assemble.h"
 #include "../type/cap.h"
@@ -740,6 +741,7 @@ static reach_type_t* add_reach_type(reach_t* r, ast_t* type)
   t->ast = set_cap_and_ephemeral(type, TK_REF, TK_NONE);
   t->ast_cap = ast_dup(type);
   t->type_id = (uint32_t)-1;
+  t->serialise_id = (uint64_t)-1;
 
   ast_set_scope(t->ast, NULL);
   ast_set_scope(t->ast_cap, NULL);
@@ -794,6 +796,15 @@ static reach_type_t* add_tuple(reach_t* r, ast_t* type, pass_opt_t* opt)
   t->type_id = get_new_tuple_id(r);
   t->can_be_boxed = true;
 
+  // TODO: ideally should be hashing AST tree for type name, fields and their types/names
+  // Only use 63/31 bits of the hash because we need the high bit for primitive types
+  if(target_is_ilp32(opt->triple))
+    t->serialise_id = (ponyint_hash_str_custom_key32(opt->serialise_id_hash_key, t->name) >> 1);
+  else
+    t->serialise_id = (ponyint_hash_str_custom_key64(opt->serialise_id_hash_key, t->name) >> 1);
+
+  pony_assert(t->serialise_id != ((uint64_t)-1)); // -1 is for `Pointer`s
+
   t->field_count = (uint32_t)ast_childcount(t->ast);
   t->fields = (reach_field_t*)ponyint_pool_alloc_size(
       t->field_count * sizeof(reach_field_t));
@@ -926,6 +937,15 @@ static reach_type_t* add_nominal(reach_t* r, ast_t* type, pass_opt_t* opt)
       t->type_id = get_new_object_id(r);
   }
 
+  // TODO: ideally should be hashing AST tree for type name, fields and their types/names
+  // Only use 63/31 bits of the hash because we need the high bit for primitive types
+  if(target_is_ilp32(opt->triple))
+    t->serialise_id = (ponyint_hash_str_custom_key32(opt->serialise_id_hash_key, t->name) >> 1);
+  else
+    t->serialise_id = (ponyint_hash_str_custom_key64(opt->serialise_id_hash_key, t->name) >> 1);
+
+  pony_assert(t->serialise_id != ((uint64_t)-1)); // -1 is for `Pointer`s
+
   if(ast_id(def) != TK_PRIMITIVE)
     return t;
 
@@ -1510,6 +1530,10 @@ void reach_dump(reach_t* r)
     size_t j = HASHMAP_BEGIN;
     reach_method_name_t* n;
 
+    printf("    serialise_id: %" PRIu64 "\n", t->serialise_id);
+    printf("    is_trait: %s\n", (t->is_trait)?"true":"false");
+    printf("    can_be_boxed: %s\n", (t->can_be_boxed)?"true":"false");
+
     printf("    vtable: %d\n", t->vtable_size);
 
     while((n = reach_method_names_next(&t->methods, &j)) != NULL)
@@ -1529,6 +1553,8 @@ void reach_dump(reach_t* r)
       printf("    %s\n", t2->name);
     }
   }
+
+  printf("  Total Type Count: %d\n", r->total_type_count);
 }
 
 static void reach_param_serialise_trace(pony_ctx_t* ctx, void* object)
@@ -1571,6 +1597,7 @@ static pony_type_t reach_param_pony =
   sizeof(reach_param_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   reach_param_serialise_trace,
@@ -1706,6 +1733,7 @@ static pony_type_t reach_method_pony =
   sizeof(reach_method_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   reach_method_serialise_trace,
@@ -1769,6 +1797,7 @@ static pony_type_t reach_method_name_pony =
   sizeof(reach_method_name_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   reach_method_name_serialise_trace,
@@ -1827,6 +1856,7 @@ static pony_type_t reach_field_pony =
   sizeof(reach_field_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   reach_field_serialise_trace,
@@ -1898,6 +1928,7 @@ static void reach_type_serialise(pony_ctx_t* ctx, void* object, void* buf,
   dst->vtable_size = t->vtable_size;
   dst->can_be_boxed = t->can_be_boxed;
   dst->is_trait = t->is_trait;
+  dst->serialise_id = t->serialise_id;
 
   dst->field_count = t->field_count;
   dst->fields = (reach_field_t*)pony_serialise_offset(ctx, t->fields);
@@ -1951,6 +1982,7 @@ static pony_type_t reach_type_pony =
   sizeof(reach_type_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   reach_type_serialise_trace,
@@ -2010,6 +2042,7 @@ static pony_type_t reach_pony =
   sizeof(reach_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   reach_serialise_trace,
diff --git a/src/libponyc/reach/reach.h b/src/libponyc/reach/reach.h
index afd0f79025..eee7f81e25 100644
--- a/src/libponyc/reach/reach.h
+++ b/src/libponyc/reach/reach.h
@@ -99,6 +99,7 @@ struct reach_type_t
   reach_type_cache_t subtypes;
   uint32_t type_id;
   uint32_t vtable_size;
+  uint64_t serialise_id;
   bool can_be_boxed;
   bool is_trait;
 
diff --git a/src/libponyc/type/reify.c b/src/libponyc/type/reify.c
index 5ad7e185d1..7a2586d3bd 100644
--- a/src/libponyc/type/reify.c
+++ b/src/libponyc/type/reify.c
@@ -561,6 +561,7 @@ static pony_type_t deferred_reification_pony =
   sizeof(deferred_reification_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   deferred_reification_serialise_trace,
diff --git a/src/libponyrt/ds/fun.c b/src/libponyrt/ds/fun.c
index a9c14d14ec..d0c36d55b7 100644
--- a/src/libponyrt/ds/fun.c
+++ b/src/libponyrt/ds/fun.c
@@ -9,8 +9,6 @@ static const unsigned char the_key[16] = {
 };
 
 
-#ifdef PLATFORM_IS_ILP32
-
 #define ROTL32(x, b) (uint32_t)(((x) << (b)) | ((x) >> (32 - (b))))
 
 #define SIPROUND32 \
@@ -76,7 +74,6 @@ static uint32_t halfsiphash24(const unsigned char* key, const unsigned char* in,
 
   return v0 ^ v1 ^ v2 ^ v3;
 }
-#endif
 
 #define ROTL64(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
 
@@ -149,6 +146,16 @@ PONY_API uint64_t ponyint_hash_block64(const void* p, size_t len)
   return siphash24(the_key, (const unsigned char*)p, len);
 }
 
+uint32_t ponyint_hash_str_custom_key32(const unsigned char* key, const char* str)
+{
+  return halfsiphash24((const unsigned char *)key, (const unsigned char *)str, strlen(str));
+}
+
+uint64_t ponyint_hash_str_custom_key64(const unsigned char* key, const char* str)
+{
+  return siphash24((const unsigned char *)key, (const unsigned char *)str, strlen(str));
+}
+
 size_t ponyint_hash_str(const char* str)
 {
 #ifdef PLATFORM_IS_ILP32
diff --git a/src/libponyrt/ds/fun.h b/src/libponyrt/ds/fun.h
index b19976bc0d..d8310e837c 100644
--- a/src/libponyrt/ds/fun.h
+++ b/src/libponyrt/ds/fun.h
@@ -25,6 +25,10 @@ PONY_API size_t ponyint_hash_block(const void* p, size_t len);
 
 PONY_API uint64_t ponyint_hash_block64(const void* p, size_t len);
 
+uint32_t ponyint_hash_str_custom_key32(const unsigned char* key, const char* str);
+
+uint64_t ponyint_hash_str_custom_key64(const unsigned char* key, const char* str);
+
 size_t ponyint_hash_str(const char* str);
 
 size_t ponyint_hash_ptr(const void* p);
diff --git a/src/libponyrt/ds/hash.h b/src/libponyrt/ds/hash.h
index 39f07138f5..7f08c17336 100644
--- a/src/libponyrt/ds/hash.h
+++ b/src/libponyrt/ds/hash.h
@@ -251,6 +251,7 @@ void ponyint_hashmap_deserialise(pony_ctx_t* ctx, void* object,
     sizeof(name_t), \
     0, \
     0, \
+    0, \
     NULL, \
     NULL, \
     name##_serialise_trace, \
diff --git a/src/libponyrt/ds/list.h b/src/libponyrt/ds/list.h
index 089927e4b2..4a829c691d 100644
--- a/src/libponyrt/ds/list.h
+++ b/src/libponyrt/ds/list.h
@@ -167,6 +167,7 @@ void ponyint_list_deserialise(pony_ctx_t* ctx, void* object,
     sizeof(name_t), \
     0, \
     0, \
+    0, \
     NULL, \
     NULL, \
     name##_serialise_trace, \
diff --git a/src/libponyrt/gc/cycle.c b/src/libponyrt/gc/cycle.c
index 349f08b1d0..6cac328459 100644
--- a/src/libponyrt/gc/cycle.c
+++ b/src/libponyrt/gc/cycle.c
@@ -1225,6 +1225,7 @@ static pony_type_t cycle_type =
   sizeof(detector_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   NULL,
diff --git a/src/libponyrt/gc/serialise.c b/src/libponyrt/gc/serialise.c
index 624e1309e3..75fbdb4aef 100644
--- a/src/libponyrt/gc/serialise.c
+++ b/src/libponyrt/gc/serialise.c
@@ -20,6 +20,7 @@ PONY_EXTERN_C_BEGIN
 
 static size_t desc_table_size = 0;
 static pony_type_t** desc_table = NULL;
+static desc_offset_lookup_fn desc_table_offset_lookup_fn = NULL;
 
 PONY_EXTERN_C_END
 
@@ -81,22 +82,38 @@ static void custom_deserialise(pony_ctx_t* ctx)
   }
 }
 
-bool ponyint_serialise_setup(pony_type_t** table, size_t table_size)
+bool ponyint_serialise_setup(pony_type_t** table, size_t table_size,
+  desc_offset_lookup_fn desc_table_offset_lookup)
 {
 #ifndef PONY_NDEBUG
   for(uint32_t i = 0; i < table_size; i++)
   {
     if(table[i] != NULL)
+    {
       pony_assert(table[i]->id == i);
+      pony_assert(desc_table_offset_lookup(table[i]->serialise_id) == i);
+    }
   }
 #endif
 
   desc_table = table;
   desc_table_size = table_size;
+  desc_table_offset_lookup_fn = desc_table_offset_lookup;
 
   return true;
 }
 
+static pony_type_t* get_descriptor(size_t serialise_id)
+{
+  uint32_t offset = desc_table_offset_lookup_fn(serialise_id);
+
+  // fail even in release builds because this is unrecoverable
+  if(offset >= desc_table_size)
+    ponyint_assert_fail("deserialise offset invalid", __FILE__, __LINE__, __func__);
+
+  return desc_table[offset];
+}
+
 void ponyint_serialise_object(pony_ctx_t* ctx, void* p, pony_type_t* t,
   int mutability)
 {
@@ -194,7 +211,7 @@ PONY_API size_t pony_serialise_offset(pony_ctx_t* ctx, void* p)
   // If we are not in the map, we are an untraced primitive. Return the type id
   // with the high bit set.
   pony_type_t* t = *(pony_type_t**)p;
-  return (size_t)t->id | HIGH_BIT;
+  return (size_t)t->serialise_id | HIGH_BIT;
 }
 
 PONY_API void pony_serialise(pony_ctx_t* ctx, void* p, pony_type_t* t,
@@ -253,7 +270,7 @@ PONY_API void* pony_deserialise_offset(pony_ctx_t* ctx, pony_type_t* t,
     // Return the global instance, if there is one. It's ok to return null if
     // there is no global instance, as this will then be an unserialised
     // field in an opaque object.
-    t = desc_table[offset];
+    t = get_descriptor(offset);
     return t->instance;
   }
 
@@ -277,9 +294,9 @@ PONY_API void* pony_deserialise_offset(pony_ctx_t* ctx, pony_type_t* t,
       abort();
     }
 
-    // Turn the type id into a descriptor pointer.
-    uintptr_t id = *(uintptr_t*)((uintptr_t)ctx->serialise_buffer + offset);
-    t = desc_table[id];
+    // Turn the serialise id into a descriptor pointer.
+    size_t id = *(uintptr_t*)((uintptr_t)ctx->serialise_buffer + offset);
+    t = get_descriptor(id);
   }
 
   // If it's a primitive, return the global instance.
diff --git a/src/libponyrt/gc/serialise.h b/src/libponyrt/gc/serialise.h
index 4a41da9af9..d31b30ad88 100644
--- a/src/libponyrt/gc/serialise.h
+++ b/src/libponyrt/gc/serialise.h
@@ -23,7 +23,8 @@ typedef struct serialise_t serialise_t;
 
 DECLARE_HASHMAP(ponyint_serialise, ponyint_serialise_t, serialise_t);
 
-bool ponyint_serialise_setup(pony_type_t** table, size_t table_size);
+bool ponyint_serialise_setup(pony_type_t** table, size_t table_size,
+  desc_offset_lookup_fn desc_table_offset_lookup);
 
 void ponyint_serialise_object(pony_ctx_t* ctx, void* p, pony_type_t* t,
   int mutability);
diff --git a/src/libponyrt/pony.h b/src/libponyrt/pony.h
index eed07d3a2e..9aaf8a0a76 100644
--- a/src/libponyrt/pony.h
+++ b/src/libponyrt/pony.h
@@ -134,6 +134,7 @@ typedef const struct _pony_type_t
 {
   uint32_t id;
   uint32_t size;
+  size_t serialise_id;
   uint32_t field_count;
   uint32_t field_offset;
   void* instance;
@@ -152,6 +153,12 @@ typedef const struct _pony_type_t
   void* vtable;
 } pony_type_t;
 
+/** Desc table lookup function.
+ *
+ * A function to convert `serialise_id`s to offsets in the desc table
+ */
+typedef uint32_t (*desc_offset_lookup_fn)(size_t serialise_id);
+
 /** Language feature initialiser.
  *
  * Contains initialisers for the various language features initialised by
@@ -178,6 +185,9 @@ typedef struct pony_language_features_init_t
 
   /// The total size of the descriptor_table array.
   size_t descriptor_table_size;
+
+  /// The function to translate `serialise_id`s to offsets in the desc_table
+  desc_offset_lookup_fn desc_table_offset_lookup;
 } pony_language_features_init_t;
 
 /// The currently executing context.
diff --git a/src/libponyrt/sched/start.c b/src/libponyrt/sched/start.c
index a7acca53fa..71d3621316 100644
--- a/src/libponyrt/sched/start.c
+++ b/src/libponyrt/sched/start.c
@@ -334,7 +334,8 @@ PONY_API bool pony_start(bool library, int* exit_code,
 
     if(language_init.init_serialisation &&
       !ponyint_serialise_setup(language_init.descriptor_table,
-        language_init.descriptor_table_size))
+        language_init.descriptor_table_size,
+        language_init.desc_table_offset_lookup))
     {
       atomic_store_explicit(&running, NOT_RUNNING, memory_order_relaxed);
       return false;
diff --git a/test/libponyrt/ds/hash.cc b/test/libponyrt/ds/hash.cc
index 4a4ea1f1c2..663dfe42c0 100644
--- a/test/libponyrt/ds/hash.cc
+++ b/test/libponyrt/ds/hash.cc
@@ -72,6 +72,7 @@ static pony_type_t hash_elem_pony =
   sizeof(hash_elem_t),
   0,
   0,
+  0,
   NULL,
   NULL,
   hash_elem_serialise_trace,