diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 3ec97dd9d11..03fdc08c8bd 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -1486,7 +1486,7 @@ Value *InstCombiner::SimplifyDemandedVectorElts(Value *V, uint64_t DemandedElts,
     bool NewUndefElts = false;
     for (unsigned i = 0; i < VWidth; i++) {
       unsigned MaskVal = Shuffle->getMaskValue(i);
-      if (MaskVal == -1) {
+      if (MaskVal == -1u) {
         uint64_t NewBit = 1ULL << i;
         UndefElts |= NewBit;
       } else if (MaskVal < VWidth) {