diff --git a/clang/lib/Basic/IdentifierTable.cpp b/clang/lib/Basic/IdentifierTable.cpp
index 102c69e..af424cd 100644
--- a/clang/lib/Basic/IdentifierTable.cpp
+++ b/clang/lib/Basic/IdentifierTable.cpp
@@ -443,9 +443,11 @@
   if (getIdentifierInfoFlag() < MultiArg) {
     IdentifierInfo *II = getAsIdentifierInfo();
 
-    // If the number of arguments is 0 then II is guaranteed to not be null.
-    if (getNumArgs() == 0)
+    if (getNumArgs() == 0) {
+      assert(II && "If the number of arguments is 0 then II is guaranteed to "
+                   "not be null.");
       return II->getName();
+    }
 
     if (!II)
       return ":";