diff --git a/payload_consumer/payload_constants.cc b/payload_consumer/payload_constants.cc
index 72abf8c..e47b4f8 100644
--- a/payload_consumer/payload_constants.cc
+++ b/payload_consumer/payload_constants.cc
@@ -52,6 +52,8 @@
       return "DISCARD";
     case InstallOperation::REPLACE_XZ:
       return "REPLACE_XZ";
+    case InstallOperation::IMGDIFF:
+      return "IMGDIFF";
   }
   return "<unknown_op>";
 }