diff --git a/src/anthropic/lib/_parse/_transform.py b/src/anthropic/lib/_parse/_transform.py
index ce0c83ac9..cc89725bd 100644
--- a/src/anthropic/lib/_parse/_transform.py
+++ b/src/anthropic/lib/_parse/_transform.py
@@ -82,14 +82,16 @@ def transform_schema(
 
     # $defs must be processed before the $ref early-return below, so that a
     # root-level `{"$ref": "#/$defs/X", "$defs": {...}}` (valid JSON Schema,
-    # and what pydantic RootModel emits) keeps its definitions.
-    defs = json_schema.pop("$defs", None)
-    if defs is not None:
-        strict_defs: dict[str, Any] = {}
-        strict_schema["$defs"] = strict_defs
-
-        for name, schema in defs.items():
-            strict_defs[name] = transform_schema(schema)
+    # and what pydantic RootModel emits) keeps its definitions. Draft-07
+    # `definitions` is the same keyword under its older name.
+    for defs_key in ("$defs", "definitions"):
+        defs = json_schema.pop(defs_key, None)
+        if defs is not None:
+            strict_defs: dict[str, Any] = {}
+            strict_schema[defs_key] = strict_defs
+
+            for name, schema in defs.items():
+                strict_defs[name] = transform_schema(schema)
 
     ref = json_schema.pop("$ref", None)
     if ref is not None:
diff --git a/tests/lib/_parse/test_transform.py b/tests/lib/_parse/test_transform.py
index 7a2799dce..214c746a9 100644
--- a/tests/lib/_parse/test_transform.py
+++ b/tests/lib/_parse/test_transform.py
@@ -40,6 +40,46 @@ def test_ref_schema_with_defs():
     )
 
 
+def test_draft07_definitions_are_kept_and_transformed():
+    schema = {
+        "type": "object",
+        "properties": {"home": {"$ref": "#/definitions/Address"}},
+        "required": ["home"],
+        "definitions": {
+            "Address": {
+                "type": "object",
+                "properties": {"city": {"type": "string"}},
+                "required": ["city"],
+            }
+        },
+    }
+    result = transform_schema(schema)
+    assert result == snapshot(
+        {
+            "definitions": {
+                "Address": {
+                    "type": "object",
+                    "properties": {"city": {"type": "string"}},
+                    "additionalProperties": False,
+                    "required": ["city"],
+                }
+            },
+            "type": "object",
+            "properties": {"home": {"$ref": "#/definitions/Address"}},
+            "additionalProperties": False,
+            "required": ["home"],
+        }
+    )
+
+
+def test_ref_schema_with_draft07_definitions():
+    schema = {"$ref": "#/definitions/Tier", "definitions": {"Tier": {"type": "string", "enum": ["free", "pro"]}}}
+    result = transform_schema(schema)
+    assert result == snapshot(
+        {"definitions": {"Tier": {"type": "string", "enum": ["free", "pro"]}}, "$ref": "#/definitions/Tier"}
+    )
+
+
 def test_anyof_schema():
     schema = {
         "anyOf": [