diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 38daeaa5bbd..9ecc8714917 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -3715,7 +3715,8 @@ SDValue ARMTargetLowering::ReconstructShuffle(SDValue Op, SelectionDAG &DAG) con
     
     // Since only 64-bit and 128-bit vectors are legal on ARM and
     // we've eliminated the other cases...
-    assert(SourceVecs[i].getValueType().getVectorNumElements() == 2*NumElts);
+    assert(SourceVecs[i].getValueType().getVectorNumElements() == 2*NumElts &&
+           "unexpected vector sizes in ReconstructShuffle");
     
     if (MaxElts[i] - MinElts[i] >= NumElts) {
       // Span too large for a VEXT to cope