diff --git a/pkg/providers/openai_compat/provider.go b/pkg/providers/openai_compat/provider.go
index f97bf3acd..5901da304 100644
--- a/pkg/providers/openai_compat/provider.go
+++ b/pkg/providers/openai_compat/provider.go
@@ -462,6 +462,10 @@ func normalizeModel(model, apiBase string) string {
 		return model
 	}
 
+	if strings.HasPrefix(strings.ToLower(model), "openrouter/") {
+		return model
+	}
+
 	if strings.Contains(strings.ToLower(apiBase), "openrouter.ai") {
 		return model
 	}
diff --git a/pkg/providers/openai_compat/provider_test.go b/pkg/providers/openai_compat/provider_test.go
index 41f278a1b..60d46d3a8 100644
--- a/pkg/providers/openai_compat/provider_test.go
+++ b/pkg/providers/openai_compat/provider_test.go
@@ -566,6 +566,9 @@ func TestNormalizeModel_UsesAPIBase(t *testing.T) {
 	if got := normalizeModel("openrouter/auto", "https://openrouter.ai/api/v1"); got != "openrouter/auto" {
 		t.Fatalf("normalizeModel(openrouter) = %q, want %q", got, "openrouter/auto")
 	}
+	if got := normalizeModel("openrouter/free", "https://gateway.example.com/v1"); got != "openrouter/free" {
+		t.Fatalf("normalizeModel(openrouter custom api_base) = %q, want %q", got, "openrouter/free")
+	}
 	if got := normalizeModel("vivgrid/managed", "https://api.vivgrid.com/v1"); got != "managed" {
 		t.Fatalf("normalizeModel(vivgrid) = %q, want %q", got, "managed")
 	}