diff --git a/enzyme/Enzyme/EnzymeLogic.cpp b/enzyme/Enzyme/EnzymeLogic.cpp
index 59f1d1b08e6..f75cef60165 100644
--- a/enzyme/Enzyme/EnzymeLogic.cpp
+++ b/enzyme/Enzyme/EnzymeLogic.cpp
@@ -5142,7 +5142,7 @@ class TruncateGenerator : public llvm::InstVisitor<TruncateGenerator> {
   void visitExtractValueInst(llvm::ExtractValueInst &EEI) { return; }
   void visitInsertValueInst(llvm::InsertValueInst &EEI) { return; }
   CallInst *createMPFRCall(llvm::IRBuilder<> &B, llvm::Instruction &I,
-                           llvm::Type *RetTy, SmallVectorImpl<Value *> &Args) {
+                           llvm::Type *RetTy, SmallVectorImpl<Value *> &ArgsIn) {
     std::string Name;
     if (auto BO = dyn_cast<BinaryOperator>(&I)) {
       Name = "binop_" + std::string(BO->getOpcodeName());
@@ -5164,8 +5164,11 @@ class TruncateGenerator : public llvm::InstVisitor<TruncateGenerator> {
     }
 
     std::string MangledName =
-        std::string("__enzyme_mpfr_") + truncation.mangleString() + "_" + Name;
+        std::string("__enzyme_mpfr_") + truncation.mangleFrom() + "_" + Name;
     auto F = newFunc->getParent()->getFunction(MangledName);
+    SmallVector<Value *> Args(ArgsIn.begin(), ArgsIn.end());
+    Args.push_back(B.getInt64(truncation.getTo().exponentWidth));
+    Args.push_back(B.getInt64(truncation.getTo().significandWidth));
     if (!F) {
       SmallVector<Type *> ArgTypes;
       for (auto Arg : Args)
@@ -5467,7 +5470,7 @@ llvm::Function *EnzymeLogic::CreateTruncateFunc(RequestContext context,
   FunctionType *FTy = FunctionType::get(NewTy, params, totrunc->isVarArg());
   std::string truncName =
       std::string("__enzyme_done_truncate_") + truncateModeStr(mode) +
-      "_func_" + truncation.mangleString() + "_" + totrunc->getName().str();
+      "_func_" + truncation.mangleTruncation() + "_" + totrunc->getName().str();
   Function *NewF = Function::Create(FTy, totrunc->getLinkage(), truncName,
                                     totrunc->getParent());
 
diff --git a/enzyme/Enzyme/EnzymeLogic.h b/enzyme/Enzyme/EnzymeLogic.h
index 190b4dabc60..ce329c429c0 100644
--- a/enzyme/Enzyme/EnzymeLogic.h
+++ b/enzyme/Enzyme/EnzymeLogic.h
@@ -297,6 +297,7 @@ enum TruncateMode { TruncMemMode, TruncOpMode, TruncOpFullModuleMode };
   case TruncOpFullModuleMode:
     return "op_full_module";
   }
+  llvm_unreachable("Invalid truncation mode");
 }
 
 struct FloatRepresentation {
@@ -366,6 +367,7 @@ struct FloatTruncation {
       llvm::report_fatal_error(
           "Float truncation `from` and `to` type must not be the same.");
   }
+  FloatRepresentation getTo() { return to;}
   unsigned getFromTypeWidth() { return from.getTypeWidth(); }
   unsigned getToTypeWidth() { return to.getTypeWidth(); }
   llvm::Type *getFromType(llvm::LLVMContext &ctx) {
@@ -388,9 +390,12 @@ struct FloatTruncation {
   bool operator<(const FloatTruncation &other) const {
     return std::tuple(from, to) < std::tuple(other.from, other.to);
   }
-  std::string mangleString() const {
+  std::string mangleTruncation() const {
     return from.to_string() + "to" + to.to_string();
   }
+  std::string mangleFrom() const {
+    return from.to_string();
+  }
 };
 
 class EnzymeLogic {