diff --git a/sntpc.c b/sntpc.c
index 61724ad..13af85a 100644
--- a/sntpc.c
+++ b/sntpc.c
@@ -249,7 +249,7 @@ int main(int argc, char * const argv[])
 			background++;
 			break;
 		case 'h':
-			printf(usage_str);
+			printf("%s", usage_str);
 			return(0);
 		case 'i':
 			interval = atoi(optarg);
@@ -267,7 +267,7 @@ int main(int argc, char * const argv[])
 		}
 	}
 	if (optind != (argc - 1)) {
-		printf(usage_str);
+		printf("%s", usage_str);
 		return 1;
 	}
 	ntphost = argv[optind];