diff --git a/include/llvm/ADT/SmallString.h b/include/llvm/ADT/SmallString.h
index 687fa2d26e2..bbc3c0526ad 100644
--- a/include/llvm/ADT/SmallString.h
+++ b/include/llvm/ADT/SmallString.h
@@ -93,12 +93,11 @@ public:
   }
 
   SmallString &append_sint(int64_t N) {
-    // TODO, wrong for minint64.
     if (N < 0) {
       this->push_back('-');
       N = -N;
     }
-    return append_uint(N);
+    return append_uint((uint64_t)N);
   }
 
 };