diff --git a/llvm/lib/Transforms/Utils/CallPromotionUtils.cpp b/llvm/lib/Transforms/Utils/CallPromotionUtils.cpp
index 5a47c1f..7141e4b 100644
--- a/llvm/lib/Transforms/Utils/CallPromotionUtils.cpp
+++ b/llvm/lib/Transforms/Utils/CallPromotionUtils.cpp
@@ -430,10 +430,11 @@
     }
   }
   for (; I < NumArgs; I++) {
-    // Vararg functions can have more arguments than paramters.
+    // Vararg functions can have more arguments than parameters.
     assert(Callee->isVarArg());
     if (CB.paramHasAttr(I, Attribute::StructRet)) {
-      *FailureReason = "SRet arg to vararg function";
+      if (FailureReason)
+        *FailureReason = "SRet arg to vararg function";
       return false;
     }
   }