diff --git a/src/IceRegAlloc.cpp b/src/IceRegAlloc.cpp
index 3601846..d2bc8fb 100644
--- a/src/IceRegAlloc.cpp
+++ b/src/IceRegAlloc.cpp
@@ -410,7 +410,7 @@
     // but is never modified.  Furthermore, overlap is only allowed
     // when preferred Variable definition instructions do not appear
     // within the current Variable's live range.
-    Variable *Prefer = NULL;
+    Variable *Prefer = nullptr;
     int32_t PreferReg = Variable::NoRegister;
     bool AllowOverlap = false;
     if (FindPreference) {