diff --git a/README.md b/README.md
index 45655dc..0c5fb22 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ Usage of wrun:
   -http-timeout duration
     	HTTP client timeout (default 5m0s)
   -url value
-    	[<OS>/<architecture>=]URL (at least one required to match)
+    	[<OS>/<architecture>=]URL (at least one required)
   -use-pre-commit-cache
     	Use pre-commit's cache dir
 
diff --git a/wrun.go b/wrun.go
index 635f46b..4b71262 100644
--- a/wrun.go
+++ b/wrun.go
@@ -135,7 +135,7 @@ type config struct {
 func parseFlags(set *flag.FlagSet, args []string) (config, error) {
 	cfg := config{}
 	cfg.urlMatches = make([]urlMatch, 0, len(args)/2+3)
-	set.Func("url", "[<OS>/<architecture>=]URL (at least one required to match)", func(s string) error {
+	set.Func("url", "[<OS>/<architecture>=]URL (at least one required)", func(s string) error {
 		pattern, ur, found := strings.Cut(s, "=")
 		if found {
 			if strings.Contains(pattern, "://") {
@@ -176,6 +176,12 @@ func parseFlags(set *flag.FlagSet, args []string) (config, error) {
 	if err := set.Parse(args); err != nil {
 		return config{}, err
 	}
+	if len(cfg.urlMatches) == 0 {
+		err := errors.New("flag must occur at least once: -url")
+		_, _ = fmt.Fprintln(set.Output(), err)
+		set.Usage()
+		return config{}, err
+	}
 	return cfg, nil
 }