diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 4ed822e..66dcf14 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -10660,6 +10660,7 @@
       Diagnosed = true;
       break;
     }
+    (void)Diagnosed;
     assert(Diagnosed && "Unable to emit ODR diagnostic.");
   }
 }