diff --git a/frontends/verific/verific.cc b/frontends/verific/verific.cc
index cf8fad8b0..7284c7cd9 100644
--- a/frontends/verific/verific.cc
+++ b/frontends/verific/verific.cc
@@ -123,7 +123,7 @@ void msg_func(msg_type_t msg_type, const char *message_id, linefile_type linefil
 			msg_type == VERIFIC_IGNORE ? "IGNORE" :
 			msg_type == VERIFIC_INFO ? "INFO" :
 			msg_type == VERIFIC_COMMENT ? "COMMENT" :
-			msg_type == VERIFIC_PROGRAM_ERROR ? "PROGRAM_ERROR" : "UNKNOWN", message_id);
+			msg_type == VERIFIC_PROGRAM_ERROR ? "PROGRAM_ERROR" : "UNKNOWN", message_id ? message_id : "");
 
 	string message = linefile ? stringf("%s:%d: ", LineFile::GetFileName(linefile), LineFile::GetLineNo(linefile)) : "";
 	message += vstringf(msg, args);