more info for debugging

diff --git a/libasn1fix/asn1fix_internal.h b/libasn1fix/asn1fix_internal.h
index 79a5cf2..d4a5e84 100644
--- a/libasn1fix/asn1fix_internal.h
+++ b/libasn1fix/asn1fix_internal.h
@@ -104,7 +104,7 @@
 		int _save_errno = errno;			\
 		if(code < 0) {					\
 			if(arg->debug)				\
-			arg->debug(code, fmt " in %s (%s@%d)",	\
+			arg->debug(code, fmt " in %s (%s:%d)",	\
 				##args,				\
 				arg->mod->source_file_name,	\
 				__FILE__, __LINE__);		\