diff --git a/tc/tc_filter.c b/tc/tc_filter.c
index a9ae424a..d70c656d 100644
--- a/tc/tc_filter.c
+++ b/tc/tc_filter.c
@@ -31,7 +31,7 @@ static void usage(void);
 static void usage(void)
 {
 	fprintf(stderr, "Usage: tc filter [ add | del | change | replace | show ] dev STRING\n");
-	fprintf(stderr, "       [ pref PRIO ] [ protocol PROTO ]\n");
+	fprintf(stderr, "       [ pref PRIO ] protocol PROTO\n");
 	fprintf(stderr, "       [ estimator INTERVAL TIME_CONSTANT ]\n");
 	fprintf(stderr, "       [ root | classid CLASSID ] [ handle FILTERID ]\n");
 	fprintf(stderr, "       [ [ FILTER_TYPE ] [ help | OPTIONS ] ]\n");
@@ -102,7 +102,7 @@ int tc_filter_modify(int cmd, unsigned flags, int argc, char **argv)
 			if (prio)
 				duparg("priority", *argv);
 			if (get_u32(&prio, *argv, 0))
-				invarg(*argv, "invalid prpriority value");
+				invarg(*argv, "invalid priority value");
 		} else if (matches(*argv, "protocol") == 0) {
 			__u16 id;
 			NEXT_ARG();
@@ -127,6 +127,11 @@ int tc_filter_modify(int cmd, unsigned flags, int argc, char **argv)
 		argc--; argv++;
 	}
 
+	if (!protocol) {
+		fprintf(stderr, "\"protocol\" is required.\n");
+		return -1;
+	}
+
 	req.t.tcm_info = TC_H_MAKE(prio<<16, protocol);
 
 	if (k[0])