diff --git a/validator/schema/upsun.json b/validator/schema/upsun.json
index bf93a72..313a98e 100644
--- a/validator/schema/upsun.json
+++ b/validator/schema/upsun.json
@@ -712,7 +712,7 @@
             "description": "A list of packages from the Upsun collection of supported runtimes and/or from NixPkgs.  \nMore information: \nhttps://docs.upsun.com/create-apps/app-reference/composable-image.html"
           }
         },
-        "oneOf": [
+        "anyOf": [
           {
             "required": [
               "type"
diff --git a/validator/validator_test.go b/validator/validator_test.go
index dc202c3..a625935 100644
--- a/validator/validator_test.go
+++ b/validator/validator_test.go
@@ -171,7 +171,7 @@ services:
 						Data: []byte(`
 applications:
   app1:
-    type: "python:3.11"
+    type: "composable:25.05"
     stack:
       - "php@8.3":
         extensions:
@@ -195,7 +195,7 @@ services:
 					},
 				},
 			},
-			wantErr: true,
+			wantErr: false,
 		},
 		{
 			name: "true-boolean",