diff --git a/sxt/cbindings/backend/BUILD b/sxt/cbindings/backend/BUILD
index a4a2e1b4..68e7860d 100644
--- a/sxt/cbindings/backend/BUILD
+++ b/sxt/cbindings/backend/BUILD
@@ -10,6 +10,7 @@ sxt_cc_component(
     with_test = False,
     deps = [
         "//sxt/proof/sumcheck:sumcheck_transcript",
+        "//sxt/proof/sumcheck2:sumcheck_transcript",
     ],
 )
 
diff --git a/sxt/cbindings/backend/callback_sumcheck_transcript.h b/sxt/cbindings/backend/callback_sumcheck_transcript.h
index 8f4c9c90..ba72f7bd 100644
--- a/sxt/cbindings/backend/callback_sumcheck_transcript.h
+++ b/sxt/cbindings/backend/callback_sumcheck_transcript.h
@@ -17,6 +17,7 @@
 #pragma once
 
 #include "sxt/proof/sumcheck/sumcheck_transcript.h"
+#include "sxt/proof/sumcheck2/sumcheck_transcript.h"
 
 namespace sxt::cbnbck {
 //--------------------------------------------------------------------------------------------------
@@ -35,6 +36,24 @@ class callback_sumcheck_transcript final : public prfsk::sumcheck_transcript {
     f_(&r, context_, polynomial.data(), static_cast<unsigned>(polynomial.size()));
   }
 
+private:
+  callback_t f_;
+  void* context_;
+};
+
+template <basfld::element T>
+class callback_sumcheck_transcript2 final : public prfsk2::sumcheck_transcript<T> {
+public:
+  using callback_t = void (*)(T* r, void* context, T* polynomial, unsigned polynomial_len);
+
+  callback_sumcheck_transcript2(callback_t f, void* context) noexcept : f_{f}, context_{context} {}
+
+  void init(size_t /*num_variables*/, size_t /*round_degree*/) noexcept override {}
+
+  void round_challenge(T& r, basct::cspan<T> polynomial) noexcept override {
+    f_(&r, context_, polynomial.data(), static_cast<unsigned>(polynomial.size()));
+  }
+
 private:
   callback_t f_;
   void* context_;