diff --git a/include/llvm/ADT/SmallVector.h b/include/llvm/ADT/SmallVector.h
index 8c29f5c498d..1ba9c41bf40 100644
--- a/include/llvm/ADT/SmallVector.h
+++ b/include/llvm/ADT/SmallVector.h
@@ -246,7 +246,7 @@ public:
   }
 #else
 private:
-  template <typename Constructor> emplace_back_impl(Constructor emplace) {
+  template <typename Constructor> void emplace_back_impl(Constructor emplace) {
     if (LLVM_UNLIKELY(this->EndX >= this->CapacityX))
       this->grow();
     emplace((void *)this->end());