diff --git a/FEXCore/Source/Utils/Allocator.cpp b/FEXCore/Source/Utils/Allocator.cpp
index 58311a3744..b254945c2e 100644
--- a/FEXCore/Source/Utils/Allocator.cpp
+++ b/FEXCore/Source/Utils/Allocator.cpp
@@ -112,14 +112,18 @@ void ReenableSBRKAllocations(void* Ptr) {
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
-void SetupHooks() {
-  Alloc64 = Alloc::OSAllocator::Create64BitAllocator();
+static void AssignHookOverrides() {
   SetJemallocMmapHook(FEX_mmap);
   SetJemallocMunmapHook(FEX_munmap);
   FEXCore::Allocator::mmap = FEX_mmap;
   FEXCore::Allocator::munmap = FEX_munmap;
 }
 
+void SetupHooks() {
+  Alloc64 = Alloc::OSAllocator::Create64BitAllocator();
+  AssignHookOverrides();
+}
+
 void ClearHooks() {
   SetJemallocMmapHook(::mmap);
   SetJemallocMunmapHook(::munmap);
@@ -300,7 +304,7 @@ fextl::vector<MemoryRegion> StealMemoryRegion(uintptr_t Begin, uintptr_t End) {
   return Regions;
 }
 
-fextl::vector<MemoryRegion> Steal48BitVA() {
+fextl::vector<MemoryRegion> Setup48BitAllocatorIfExists() {
   size_t Bits = FEXCore::Allocator::DetermineVASize();
   if (Bits < 48) {
     return {};
@@ -308,7 +312,12 @@ fextl::vector<MemoryRegion> Steal48BitVA() {
 
   uintptr_t Begin48BitVA = 0x0'8000'0000'0000ULL;
   uintptr_t End48BitVA = 0x1'0000'0000'0000ULL;
-  return StealMemoryRegion(Begin48BitVA, End48BitVA);
+  auto Regions = StealMemoryRegion(Begin48BitVA, End48BitVA);
+
+  Alloc64 = Alloc::OSAllocator::Create64BitAllocatorWithRegions(Regions);
+  AssignHookOverrides();
+
+  return Regions;
 }
 
 void ReclaimMemoryRegion(const fextl::vector<MemoryRegion>& Regions) {
diff --git a/FEXCore/Source/Utils/Allocator/64BitAllocator.cpp b/FEXCore/Source/Utils/Allocator/64BitAllocator.cpp
index 60d6545c05..928ca9cd94 100644
--- a/FEXCore/Source/Utils/Allocator/64BitAllocator.cpp
+++ b/FEXCore/Source/Utils/Allocator/64BitAllocator.cpp
@@ -7,6 +7,8 @@
 #include <FEXCore/Utils/MathUtils.h>
 #include <FEXCore/Utils/SignalScopeGuards.h>
 #include <FEXCore/Utils/TypeDefines.h>
+#include <FEXCore/Utils/LogManager.h>
+#include <FEXCore/Utils/MathUtils.h>
 #include <FEXCore/fextl/sstream.h>
 #include <FEXHeaderUtils/Syscalls.h>
 #include <FEXCore/fextl/memory.h>
@@ -35,6 +37,8 @@ thread_local FEXCore::Core::InternalThreadState* TLSThread {};
 class OSAllocator_64Bit final : public Alloc::HostAllocator {
 public:
   OSAllocator_64Bit();
+  OSAllocator_64Bit(fextl::vector<FEXCore::Allocator::MemoryRegion>& Regions);
+
   virtual ~OSAllocator_64Bit();
   void* AllocateSlab(size_t Size) override {
     return nullptr;
@@ -99,19 +103,20 @@ class OSAllocator_64Bit final : public Alloc::HostAllocator {
     // This returns the size of the LiveVMARegion in addition to the flex set that tracks the used data
     // The LiveVMARegion lives at the start of the VMA region which means on initialization we need to set that
     // tracked ranged as used immediately
-    static size_t GetSizeWithFlexSet(size_t Size) {
+    static size_t GetFEXManagedVMARegionSize(size_t Size) {
       // One element per page
 
       // 0x10'0000'0000 bytes
       // 0x100'0000 Pages
       // 1 bit per page for tracking means 0x20'0000 (Pages / 8) bytes of flex space
       // Which is 2MB of tracking
-      uint64_t NumElements = (Size >> FEXCore::Utils::FEX_PAGE_SHIFT) * sizeof(FlexBitElementType);
-      return sizeof(LiveVMARegion) + FEXCore::FlexBitSet<FlexBitElementType>::Size(NumElements);
+      const uint64_t NumElements = Size >> FEXCore::Utils::FEX_PAGE_SHIFT;
+      return sizeof(LiveVMARegion) + FEXCore::FlexBitSet<FlexBitElementType>::SizeInBytes(NumElements);
     }
 
     static void InitializeVMARegionUsed(LiveVMARegion* Region, size_t AdditionalSize) {
-      size_t SizeOfLiveRegion = FEXCore::AlignUp(LiveVMARegion::GetSizeWithFlexSet(Region->SlabInfo->RegionSize), FEXCore::Utils::FEX_PAGE_SIZE);
+      size_t SizeOfLiveRegion =
+        FEXCore::AlignUp(LiveVMARegion::GetFEXManagedVMARegionSize(Region->SlabInfo->RegionSize), FEXCore::Utils::FEX_PAGE_SIZE);
       size_t SizePlusManagedData = SizeOfLiveRegion + AdditionalSize;
 
       Region->FreeSpace = Region->SlabInfo->RegionSize - SizePlusManagedData;
@@ -155,7 +160,8 @@ class OSAllocator_64Bit final : public Alloc::HostAllocator {
     ReservedRegions->erase(ReservedIterator);
 
     // mprotect the new region we've allocated
-    size_t SizeOfLiveRegion = FEXCore::AlignUp(LiveVMARegion::GetSizeWithFlexSet(ReservedRegion->RegionSize), FEXCore::Utils::FEX_PAGE_SIZE);
+    size_t SizeOfLiveRegion =
+      FEXCore::AlignUp(LiveVMARegion::GetFEXManagedVMARegionSize(ReservedRegion->RegionSize), FEXCore::Utils::FEX_PAGE_SIZE);
     size_t SizePlusManagedData = UsedSize + SizeOfLiveRegion;
 
     [[maybe_unused]] auto Res = mprotect(reinterpret_cast<void*>(ReservedRegion->Base), SizePlusManagedData, PROT_READ | PROT_WRITE);
@@ -180,7 +186,7 @@ class OSAllocator_64Bit final : public Alloc::HostAllocator {
   // 32-bit old kernel workarounds
   fextl::vector<FEXCore::Allocator::MemoryRegion> Steal32BitIfOldKernel();
 
-  void AllocateMemoryRegions(const fextl::vector<FEXCore::Allocator::MemoryRegion>& Ranges);
+  void AllocateMemoryRegions(fextl::vector<FEXCore::Allocator::MemoryRegion>& Ranges);
   LiveVMARegion* FindLiveRegionForAddress(uintptr_t Addr, uintptr_t AddrEnd);
 };
 
@@ -383,7 +389,7 @@ void* OSAllocator_64Bit::Mmap(void* addr, size_t length, int prot, int flags, in
     if (!LiveRegion) {
       // Couldn't find a fit in the live regions
       // Allocate a new reserved region
-      size_t lengthOfLiveRegion = FEXCore::AlignUp(LiveVMARegion::GetSizeWithFlexSet(length), FEXCore::Utils::FEX_PAGE_SIZE);
+      size_t lengthOfLiveRegion = FEXCore::AlignUp(LiveVMARegion::GetFEXManagedVMARegionSize(length), FEXCore::Utils::FEX_PAGE_SIZE);
       size_t lengthPlusManagedData = length + lengthOfLiveRegion;
       for (auto it = ReservedRegions->begin(); it != ReservedRegions->end(); ++it) {
         if ((*it)->RegionSize >= lengthPlusManagedData) {
@@ -515,27 +521,43 @@ fextl::vector<FEXCore::Allocator::MemoryRegion> OSAllocator_64Bit::Steal32BitIfO
   return FEXCore::Allocator::StealMemoryRegion(LOWER_BOUND_32, UPPER_BOUND_32);
 }
 
-void OSAllocator_64Bit::AllocateMemoryRegions(const fextl::vector<FEXCore::Allocator::MemoryRegion>& Ranges) {
-  for (auto [Ptr, AllocationSize] : Ranges) {
-    if (!ObjectAlloc) {
-      auto MaxSize = std::min(size_t(64) * 1024 * 1024, AllocationSize);
+void OSAllocator_64Bit::AllocateMemoryRegions(fextl::vector<FEXCore::Allocator::MemoryRegion>& Ranges) {
+  // Need to allocate the ObjectAlloc up front. Find a region that is larger than our minimum size first.
+  const size_t ObjectAllocSize = 64 * 1024 * 1024;
+
+  for (auto& it : Ranges) {
+    if (ObjectAllocSize > it.Size) {
+      continue;
+    }
 
-      // Allocate up to 64 MiB the first allocation for an intrusive allocator
-      mprotect(Ptr, MaxSize, PROT_READ | PROT_WRITE);
+    // Allocate up to 64 MiB the first allocation for an intrusive allocator
+    mprotect(it.Ptr, ObjectAllocSize, PROT_READ | PROT_WRITE);
 
-      // This enables the kernel to use transparent large pages in the allocator which can reduce memory pressure
-      ::madvise(Ptr, MaxSize, MADV_HUGEPAGE);
+    // This enables the kernel to use transparent large pages in the allocator which can reduce memory pressure
+    ::madvise(it.Ptr, ObjectAllocSize, MADV_HUGEPAGE);
 
-      ObjectAlloc = new (Ptr) Alloc::ForwardOnlyIntrusiveArenaAllocator(Ptr, MaxSize);
-      ReservedRegions = ObjectAlloc->new_construct(ReservedRegions, ObjectAlloc);
-      LiveRegions = ObjectAlloc->new_construct(LiveRegions, ObjectAlloc);
+    ObjectAlloc = new (it.Ptr) Alloc::ForwardOnlyIntrusiveArenaAllocator(it.Ptr, ObjectAllocSize);
+    ReservedRegions = ObjectAlloc->new_construct(ReservedRegions, ObjectAlloc);
+    LiveRegions = ObjectAlloc->new_construct(LiveRegions, ObjectAlloc);
 
-      if (AllocationSize > MaxSize) {
-        AllocationSize -= MaxSize;
-        (uint8_t*&)Ptr += MaxSize;
-      } else {
-        continue;
-      }
+    if (it.Size >= ObjectAllocSize) {
+      // Modify region size
+      it.Size -= ObjectAllocSize;
+      (uint8_t*&)it.Ptr += ObjectAllocSize;
+    }
+
+    break;
+  }
+
+  if (!ObjectAlloc) {
+    ERROR_AND_DIE_FMT("Couldn't allocate object allocator!");
+  }
+
+  for (auto [Ptr, AllocationSize] : Ranges) {
+    // Skip using any regions that are <= two pages. FEX's VMA allocator requires two pages
+    // for tracking data. So three pages are minimum for a single page VMA allocation.
+    if (AllocationSize <= (FEXCore::Utils::FEX_PAGE_SIZE * 2)) {
+      continue;
     }
 
     ReservedVMARegion* Region = ObjectAlloc->new_construct<ReservedVMARegion>();
@@ -557,6 +579,10 @@ OSAllocator_64Bit::OSAllocator_64Bit() {
   FEXCore::Allocator::ReclaimMemoryRegion(LowMem);
 }
 
+OSAllocator_64Bit::OSAllocator_64Bit(fextl::vector<FEXCore::Allocator::MemoryRegion>& Regions) {
+  AllocateMemoryRegions(Regions);
+}
+
 OSAllocator_64Bit::~OSAllocator_64Bit() {
   // This needs a mutex to be thread safe
   auto lk = FEXCore::GuardSignalDeferringSectionWithFallback(AllocationMutex, TLSThread);
@@ -576,6 +602,62 @@ OSAllocator_64Bit::~OSAllocator_64Bit() {
 fextl::unique_ptr<Alloc::HostAllocator> Create64BitAllocator() {
   return fextl::make_unique<OSAllocator_64Bit>();
 }
+
+template<class T>
+struct alloc_delete : public std::default_delete<T> {
+  void operator()(T* ptr) const {
+    if (ptr) {
+      const auto size = sizeof(T);
+      const auto MinPage = FEXCore::AlignUp(size, FEXCore::Utils::FEX_PAGE_SIZE);
+
+      std::destroy_at(ptr);
+      ::munmap(ptr, MinPage);
+    }
+  }
+
+  template<typename U>
+  requires (std::is_base_of_v<U, T>)
+  operator fextl::default_delete<U>() {
+    return fextl::default_delete<U>();
+  }
+};
+
+template<class T, class... Args>
+requires (!std::is_array_v<T>)
+fextl::unique_ptr<T> make_alloc_unique(FEXCore::Allocator::MemoryRegion& Base, Args&&... args) {
+  const auto size = sizeof(T);
+  const auto MinPage = FEXCore::AlignUp(size, FEXCore::Utils::FEX_PAGE_SIZE);
+  if (Base.Size < size || MinPage != FEXCore::Utils::FEX_PAGE_SIZE) {
+    ERROR_AND_DIE_FMT("Couldn't fit allocator in to page!");
+  }
+
+  auto ptr = ::mmap(Base.Ptr, MinPage, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+  if (ptr == MAP_FAILED) {
+    ERROR_AND_DIE_FMT("Couldn't allocate memory region");
+  }
+
+  // Remove the page from the base region.
+  // Could be zero after this.
+  Base.Size -= MinPage;
+  Base.Ptr = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(Base.Ptr) + MinPage);
+
+  auto Result = ::new (ptr) T(std::forward<Args>(args)...);
+  return fextl::unique_ptr<T, alloc_delete<T>>(Result);
+}
+
+fextl::unique_ptr<Alloc::HostAllocator> Create64BitAllocatorWithRegions(fextl::vector<FEXCore::Allocator::MemoryRegion>& Regions) {
+  // This is a bit tricky as we can't allocate memory safely except from the Regions provided. Otherwise we might overwrite memory pages we
+  // don't own. Scan the memory regions and find the smallest one.
+  FEXCore::Allocator::MemoryRegion& Smallest = Regions[0];
+  for (auto& it : Regions) {
+    if (it.Size <= Smallest.Size) {
+      Smallest = it;
+    }
+  }
+
+  return make_alloc_unique<OSAllocator_64Bit>(Smallest, Regions);
+}
+
 } // namespace Alloc::OSAllocator
 
 namespace FEXCore::Allocator {
diff --git a/FEXCore/Source/Utils/Allocator/FlexBitSet.h b/FEXCore/Source/Utils/Allocator/FlexBitSet.h
index 57fe6280da..f15de92582 100644
--- a/FEXCore/Source/Utils/Allocator/FlexBitSet.h
+++ b/FEXCore/Source/Utils/Allocator/FlexBitSet.h
@@ -145,8 +145,14 @@ struct FlexBitSet final {
     return Get(Element);
   }
 
-  static size_t Size(uint64_t Elements) {
-    return FEXCore::AlignUp(Elements / MinimumSizeBits, MinimumSizeBits);
+  // Returns the number of bits required to hold the number of elements.
+  // Just rounds up to the MinimumSizeInBits.
+  constexpr static size_t SizeInBits(uint64_t Elements) {
+    return FEXCore::AlignUp(Elements, MinimumSizeBits);
+  }
+  // Returns the number of bytes required to hold the number of elements.
+  constexpr static size_t SizeInBytes(uint64_t Elements) {
+    return SizeInBits(Elements) / 8;
   }
 };
 
diff --git a/FEXCore/Source/Utils/Allocator/HostAllocator.h b/FEXCore/Source/Utils/Allocator/HostAllocator.h
index 445722de7b..a3e4648923 100644
--- a/FEXCore/Source/Utils/Allocator/HostAllocator.h
+++ b/FEXCore/Source/Utils/Allocator/HostAllocator.h
@@ -2,9 +2,10 @@
 #pragma once
 #include <FEXCore/fextl/allocator.h>
 #include <FEXCore/fextl/memory.h>
+#include <FEXCore/fextl/vector.h>
+#include <FEXCore/Utils/Allocator.h>
 
 #include <cstddef>
-#include <cstdint>
 #include <sys/types.h>
 
 namespace FEXCore::Core {
@@ -49,4 +50,5 @@ class GlobalAllocator {
 
 namespace Alloc::OSAllocator {
 fextl::unique_ptr<Alloc::HostAllocator> Create64BitAllocator();
+fextl::unique_ptr<Alloc::HostAllocator> Create64BitAllocatorWithRegions(fextl::vector<FEXCore::Allocator::MemoryRegion>& Regions);
 } // namespace Alloc::OSAllocator
diff --git a/FEXCore/include/FEXCore/Utils/Allocator.h b/FEXCore/include/FEXCore/Utils/Allocator.h
index 795aff1aaa..524288242f 100644
--- a/FEXCore/include/FEXCore/Utils/Allocator.h
+++ b/FEXCore/include/FEXCore/Utils/Allocator.h
@@ -86,7 +86,7 @@ FEX_DEFAULT_VISIBILITY void ReclaimMemoryRegion(const fextl::vector<MemoryRegion
 // AArch64 canonical addresses are only up to bits 48/52 with the remainder being other things
 // Use this to reserve the top 128TB of VA so the guest never see it
 // Returns nullptr on host VA < 48bits
-FEX_DEFAULT_VISIBILITY fextl::vector<MemoryRegion> Steal48BitVA();
+FEX_DEFAULT_VISIBILITY fextl::vector<MemoryRegion> Setup48BitAllocatorIfExists();
 
 #ifndef _WIN32
 FEX_DEFAULT_VISIBILITY void RegisterTLSData(FEXCore::Core::InternalThreadState* Thread);
diff --git a/FEXCore/unittests/APITests/FlexBitSet.cpp b/FEXCore/unittests/APITests/FlexBitSet.cpp
new file mode 100644
index 0000000000..98355e9b09
--- /dev/null
+++ b/FEXCore/unittests/APITests/FlexBitSet.cpp
@@ -0,0 +1,41 @@
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/generators/catch_generators_range.hpp>
+
+#include "Utils/Allocator/FlexBitSet.h"
+
+TEST_CASE("FlexBitSet - Sizing") {
+  // Ensure that FlexBitSet sizing is correct.
+
+  // Size of zero shouldn't take any space.
+  CHECK(FEXCore::FlexBitSet<uint8_t>::SizeInBytes(0) == 0);
+  CHECK(FEXCore::FlexBitSet<uint16_t>::SizeInBytes(0) == 0);
+  CHECK(FEXCore::FlexBitSet<uint32_t>::SizeInBytes(0) == 0);
+  CHECK(FEXCore::FlexBitSet<uint64_t>::SizeInBytes(0) == 0);
+
+  CHECK(FEXCore::FlexBitSet<uint8_t>::SizeInBits(0) == 0);
+  CHECK(FEXCore::FlexBitSet<uint16_t>::SizeInBits(0) == 0);
+  CHECK(FEXCore::FlexBitSet<uint32_t>::SizeInBits(0) == 0);
+  CHECK(FEXCore::FlexBitSet<uint64_t>::SizeInBits(0) == 0);
+
+  // Size of 1 should take one sizeof(ElementSize) size
+  CHECK(FEXCore::FlexBitSet<uint8_t>::SizeInBytes(1) == sizeof(uint8_t));
+  CHECK(FEXCore::FlexBitSet<uint16_t>::SizeInBytes(1) == sizeof(uint16_t));
+  CHECK(FEXCore::FlexBitSet<uint32_t>::SizeInBytes(1) == sizeof(uint32_t));
+  CHECK(FEXCore::FlexBitSet<uint64_t>::SizeInBytes(1) == sizeof(uint64_t));
+
+  CHECK(FEXCore::FlexBitSet<uint8_t>::SizeInBits(1) == sizeof(uint8_t) * 8);
+  CHECK(FEXCore::FlexBitSet<uint16_t>::SizeInBits(1) == sizeof(uint16_t) * 8);
+  CHECK(FEXCore::FlexBitSet<uint32_t>::SizeInBits(1) == sizeof(uint32_t) * 8);
+  CHECK(FEXCore::FlexBitSet<uint64_t>::SizeInBits(1) == sizeof(uint64_t) * 8);
+
+  // Size of `sizeof(ElementSize) * 8` should take one sizeof(ElementSize) size
+  CHECK(FEXCore::FlexBitSet<uint8_t>::SizeInBytes(sizeof(uint8_t) * 8) == sizeof(uint8_t));
+  CHECK(FEXCore::FlexBitSet<uint16_t>::SizeInBytes(sizeof(uint16_t) * 8) == sizeof(uint16_t));
+  CHECK(FEXCore::FlexBitSet<uint32_t>::SizeInBytes(sizeof(uint32_t) * 8) == sizeof(uint32_t));
+  CHECK(FEXCore::FlexBitSet<uint64_t>::SizeInBytes(sizeof(uint64_t) * 8) == sizeof(uint64_t));
+
+  CHECK(FEXCore::FlexBitSet<uint8_t>::SizeInBits(sizeof(uint8_t) * 8) == sizeof(uint8_t) * 8);
+  CHECK(FEXCore::FlexBitSet<uint16_t>::SizeInBits(sizeof(uint16_t) * 8) == sizeof(uint16_t) * 8);
+  CHECK(FEXCore::FlexBitSet<uint32_t>::SizeInBits(sizeof(uint32_t) * 8) == sizeof(uint32_t) * 8);
+  CHECK(FEXCore::FlexBitSet<uint64_t>::SizeInBits(sizeof(uint64_t) * 8) == sizeof(uint64_t) * 8);
+}
diff --git a/Source/Tools/FEXLoader/FEXLoader.cpp b/Source/Tools/FEXLoader/FEXLoader.cpp
index dd0aec576c..53bf90cf41 100644
--- a/Source/Tools/FEXLoader/FEXLoader.cpp
+++ b/Source/Tools/FEXLoader/FEXLoader.cpp
@@ -496,7 +496,7 @@ int main(int argc, char** argv, char** const envp) {
 
   if (Loader.Is64BitMode()) {
     // Destroy the 48th bit if it exists
-    Base48Bit = FEXCore::Allocator::Steal48BitVA();
+    Base48Bit = FEXCore::Allocator::Setup48BitAllocatorIfExists();
   } else {
     // Reserve [0x1_0000_0000, 0x2_0000_0000).
     // Safety net if 32-bit address calculation overflows in to 64-bit range.