diff --git a/llvm/lib/FuzzMutate/IRMutator.cpp b/llvm/lib/FuzzMutate/IRMutator.cpp
index 7e28f58046b1f..13fc7b11b67eb 100644
--- a/llvm/lib/FuzzMutate/IRMutator.cpp
+++ b/llvm/lib/FuzzMutate/IRMutator.cpp
@@ -390,6 +390,7 @@ void InsertFunctionStrategy::mutate(BasicBlock &BB, RandomIRBuilder &IB) {
                                          BasicBlock::iterator InsertPt) {
     StringRef Name = isRetVoid ? nullptr : "C";
     CallInst *Call = CallInst::Create(FTy, F, Srcs, Name, InsertPt);
+    Call->setCallingConv(F->getCallingConv());
     // Don't return this call inst if it return void as it can't be sinked.
     return isRetVoid ? nullptr : Call;
   };