diff --git a/tools/llvm-diff/DifferenceEngine.cpp b/tools/llvm-diff/DifferenceEngine.cpp
index 2344e39..ba2cec2 100644
--- a/tools/llvm-diff/DifferenceEngine.cpp
+++ b/tools/llvm-diff/DifferenceEngine.cpp
@@ -267,7 +267,7 @@
     } else if (isa<PHINode>(L)) {
       // FIXME: implement.
 
-      // This is really wierd;  type uniquing is broken?
+      // This is really weird;  type uniquing is broken?
       if (L->getType() != R->getType()) {
         if (!L->getType()->isPointerTy() || !R->getType()->isPointerTy()) {
           if (Complain) Engine.log("different phi types");