diff --git a/src/libcharon/plugins/tnccs_20/messages/pb_tnc_msg.h b/src/libcharon/plugins/tnccs_20/messages/pb_tnc_msg.h
index e20c8d8ff..97ebed27f 100644
--- a/src/libcharon/plugins/tnccs_20/messages/pb_tnc_msg.h
+++ b/src/libcharon/plugins/tnccs_20/messages/pb_tnc_msg.h
@@ -56,7 +56,7 @@ struct pb_tnc_msg_info_t {
 	u_int32_t min_size;
 	bool exact_size;
 	bool in_result_batch;
-	bool has_noskip_flag;
+	signed char has_noskip_flag;
 };
 
 #define	TRUE_OR_FALSE	2