diff --git a/.changelog/5708.bugfix.md b/.changelog/5708.bugfix.md
new file mode 100644
index 00000000000..c82e1063f7f
--- /dev/null
+++ b/.changelog/5708.bugfix.md
@@ -0,0 +1 @@
+go/registry/api: update ProveFreshness tx body type
diff --git a/go/registry/api/api.go b/go/registry/api/api.go
index c13b5a90f84..a45ae7246e7 100644
--- a/go/registry/api/api.go
+++ b/go/registry/api/api.go
@@ -131,7 +131,7 @@ var (
 	// MethodRegisterRuntime is the method name for registering runtimes.
 	MethodRegisterRuntime = transaction.NewMethodName(ModuleName, "RegisterRuntime", Runtime{})
 	// MethodProveFreshness is the method name for freshness proofs.
-	MethodProveFreshness = transaction.NewMethodName(ModuleName, "ProveFreshness", Runtime{})
+	MethodProveFreshness = transaction.NewMethodName(ModuleName, "ProveFreshness", [32]byte{})
 
 	// Methods is the list of all methods supported by the registry backend.
 	Methods = []transaction.MethodName{