diff --git a/db/merge_helper.cc b/db/merge_helper.cc
index 0f73576c0..b03e9dafe 100644
--- a/db/merge_helper.cc
+++ b/db/merge_helper.cc
@@ -138,7 +138,11 @@ Status MergeHelper::MergeUntil(InternalIterator* iter,
   // orig_ikey is backed by original_key if keys_.empty()
   // orig_ikey is backed by keys_.back() if !keys_.empty()
   ParsedInternalKey orig_ikey;
-  ParseInternalKey(original_key, &orig_ikey);
+  bool succ = ParseInternalKey(original_key, &orig_ikey);
+  assert(succ);
+  if (!succ) {
+    return Status::Corruption("Cannot parse key in MergeUntil");
+  }
 
   Status s;
   bool hit_the_next_user_key = false;