diff --git a/apistar/schemas/jsonschema.py b/apistar/schemas/jsonschema.py
index d649f2cc..9d62eb17 100644
--- a/apistar/schemas/jsonschema.py
+++ b/apistar/schemas/jsonschema.py
@@ -1,6 +1,6 @@
 import typesystem
 
-definitions = typesystem.SchemaDefinitions()
+definitions = typesystem.Definitions()
 
 JSON_SCHEMA = (
     typesystem.Object(
diff --git a/requirements.txt b/requirements.txt
index cf3a4712..1e2c3002 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,7 +3,7 @@ click
 jinja2
 requests
 pyyaml
-typesystem>=0.2.0
+typesystem>=0.3.0
 
 # Testing requirements
 black