diff --git a/pattern.go b/pattern.go
index 7a1a14e..0139678 100644
--- a/pattern.go
+++ b/pattern.go
@@ -17,6 +17,7 @@ import (
 
 func TemplatePatterns(ts *template.Template) ([]Pattern, error) {
 	var patterns []Pattern
+	routes := make(map[string]struct{})
 	for _, t := range ts.Templates() {
 		pat, err, ok := NewPattern(t.Name())
 		if !ok {
@@ -25,9 +26,10 @@ func TemplatePatterns(ts *template.Template) ([]Pattern, error) {
 		if err != nil {
 			return patterns, err
 		}
-		if slices.ContainsFunc(patterns, pat.sameRoute) {
+		if _, exists := routes[pat.Method+pat.Path]; exists {
 			return patterns, fmt.Errorf("duplicate route pattern: %s", pat.Route)
 		}
+		routes[pat.Method+pat.Path] = struct{}{}
 		patterns = append(patterns, pat)
 	}
 	slices.SortFunc(patterns, Pattern.byPathThenMethod)
diff --git a/pattern_test.go b/pattern_test.go
index 7d3e55e..4cbdbb3 100644
--- a/pattern_test.go
+++ b/pattern_test.go
@@ -1,6 +1,7 @@
 package muxt_test
 
 import (
+	"html/template"
 	"net/http"
 	"testing"
 
@@ -10,6 +11,19 @@ import (
 	"github.com/crhntr/muxt"
 )
 
+func TestTemplatePatterns(t *testing.T) {
+	t.Run("when one of the template names is a malformed pattern", func(t *testing.T) {
+		ts := template.Must(template.New("").Parse(`{{define "HEAD /"}}{{end}}`))
+		_, err := muxt.TemplatePatterns(ts)
+		require.Error(t, err)
+	})
+	t.Run("when the pattern is not unique", func(t *testing.T) {
+		ts := template.Must(template.New("").Parse(`{{define "GET  / F1()"}}a{{end}} {{define "GET /  F2()"}}b{{end}}`))
+		_, err := muxt.TemplatePatterns(ts)
+		require.Error(t, err)
+	})
+}
+
 func TestNewPattern(t *testing.T) {
 	for _, tt := range []struct {
 		Name         string