diff --git a/crates/uv-normalize/src/group_name.rs b/crates/uv-normalize/src/group_name.rs
index 124079c08ee32..405907c1fc2ea 100644
--- a/crates/uv-normalize/src/group_name.rs
+++ b/crates/uv-normalize/src/group_name.rs
@@ -1,3 +1,5 @@
+#[cfg(feature = "schemars")]
+use std::borrow::Cow;
 use std::fmt::{Display, Formatter};
 use std::path::PathBuf;
 use std::str::FromStr;
@@ -173,7 +175,6 @@ impl Display for PipGroupName {
 
 /// Either the literal "all" or a list of groups
 #[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
-#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub enum DefaultGroups {
     /// All groups are defaulted
     All,
@@ -181,6 +182,31 @@ pub enum DefaultGroups {
     List(Vec<GroupName>),
 }
 
+#[cfg(feature = "schemars")]
+impl schemars::JsonSchema for DefaultGroups {
+    fn schema_name() -> Cow<'static, str> {
+        Cow::Borrowed("DefaultGroups")
+    }
+
+    fn json_schema(generator: &mut schemars::generate::SchemaGenerator) -> schemars::Schema {
+        schemars::json_schema!({
+            "description": "Either the literal \"all\" or a list of groups",
+            "oneOf": [
+                {
+                    "description": "All groups are defaulted",
+                    "type": "string",
+                    "const": "all"
+                },
+                {
+                    "description": "A list of groups",
+                    "type": "array",
+                    "items": generator.subschema_for::<GroupName>()
+                }
+            ]
+        })
+    }
+}
+
 /// Serialize a [`DefaultGroups`] struct into a list of marker strings.
 impl serde::Serialize for DefaultGroups {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
diff --git a/uv.schema.json b/uv.schema.json
index d16e4a1aabe14..b475bbd7ad583 100644
--- a/uv.schema.json
+++ b/uv.schema.json
@@ -857,23 +857,14 @@
         {
           "description": "All groups are defaulted",
           "type": "string",
-          "const": "All"
+          "const": "all"
         },
         {
           "description": "A list of groups",
-          "type": "object",
-          "properties": {
-            "List": {
-              "type": "array",
-              "items": {
-                "$ref": "#/definitions/GroupName"
-              }
-            }
-          },
-          "additionalProperties": false,
-          "required": [
-            "List"
-          ]
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/GroupName"
+          }
         }
       ]
     },