--- src/libspf2/spf_id2str.c.orig	Wed Apr 19 18:36:58 2017
+++ src/libspf2/spf_id2str.c	Wed Apr 19 18:37:08 2017
@@ -52,7 +52,7 @@ SPF_record_stringify_data(SPF_data_t *data, SPF_data_t
 	SPF_data_t		*cidr_data;
 
 	if (debug)
-		SPF_debugf(" string data: Building");
+		SPF_debugf("%s", " string data: Building");
 
 	if (p_end - p <= 0)
 		return SPF_E_INTERNAL_ERROR;