diff --git a/src/gmmpp_msgs.erl b/src/gmmpp_msgs.erl
index 25f97a3..e93707b 100644
--- a/src/gmmpp_msgs.erl
+++ b/src/gmmpp_msgs.erl
@@ -219,6 +219,7 @@ error_code(invalid_prefix   ) -> -32005;
 error_code(invalid_encoding ) -> -32006;
 error_code(outdated         ) -> -32007;
 error_code(solution_mismatch) -> -32008;
+error_code(invalid_input    ) -> -32009;
 error_code(unknown_method   ) -> -32601;
 error_code(_                ) -> -32603.   % internal error