--- src/libspf2/spf_dns_zone.c.orig	Wed Apr 19 18:36:06 2017
+++ src/libspf2/spf_dns_zone.c	Wed Apr 19 18:36:36 2017
@@ -114,7 +114,7 @@ SPF_dns_zone_find(SPF_dns_server_t *spf_dns_server,
 				return spfhook->zone[i];
 		}
 		if (spf_dns_server->debug)
-			SPF_debugf("zone: Exact not found");
+			SPF_debugf("%s", "zone: Exact not found");
     }
 	else {
 		/* We are looking up a record, so lookup-matching semantics apply. */
@@ -152,7 +152,7 @@ SPF_dns_zone_find(SPF_dns_server_t *spf_dns_server,
 			}
 		}
 		if (spf_dns_server->debug)
-			SPF_debugf("zone: Non-exact not found");
+			SPF_debugf("%s", "zone: Non-exact not found");
 	}
 
     return NULL;
