diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 9257191..c4a548f 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -804,7 +804,7 @@
     SlotIndex BlockStart = getMBBStartIdx(MBB);
 
     // Extend the live range for VNI to be live at Idx.
-    if (VNInfo *ExtVNI = NewLI.extendInBlock(BlockStart, Idx)) {
+    if (VNInfo *ExtVNI = NewLI.extendInBlock(BlockStart, Idx.getNextSlot())) {
       (void)ExtVNI;
       assert(ExtVNI == VNI && "Unexpected existing value number");
       // Is this a PHIDef we haven't seen before?