diff --git a/llvm/lib/FuzzMutate/IRMutator.cpp b/llvm/lib/FuzzMutate/IRMutator.cpp
--- a/llvm/lib/FuzzMutate/IRMutator.cpp
+++ b/llvm/lib/FuzzMutate/IRMutator.cpp
@@ -355,7 +355,7 @@
 
   FunctionType *FTy = F->getFunctionType();
   SmallVector<fuzzerop::SourcePred, 2> SourcePreds;
-  if (F->arg_empty()) {
+  if (!F->arg_empty()) {
     for (Type *ArgTy : FTy->params()) {
       SourcePreds.push_back(fuzzerop::onlyType(ArgTy));
     }