diff --git a/llvm/include/llvm/CodeGen/SlotIndexes.h b/llvm/include/llvm/CodeGen/SlotIndexes.h
index 10ab4cca8319..2b32a4d30dff 100644
--- a/llvm/include/llvm/CodeGen/SlotIndexes.h
+++ b/llvm/include/llvm/CodeGen/SlotIndexes.h
@@ -347,7 +347,7 @@ class raw_ostream;
   public:
     static char ID;
 
-    SlotIndexes() : MachineFunctionPass(ID) {
+    SlotIndexes() : MachineFunctionPass(ID), mf(nullptr) {
       initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
     }