diff --git a/src/core/resolvers/schema-definition.ts b/src/core/resolvers/schema-definition.ts
index b9358f7..3217874 100644
--- a/src/core/resolvers/schema-definition.ts
+++ b/src/core/resolvers/schema-definition.ts
@@ -45,6 +45,7 @@ export function resolveSchema(definition?: SchemaObject): string {
     }
     case "number": return "number";
     case "boolean": return "boolean";
+    case "null": return "null";
     case "array": {
       if (definition.maxItems && definition.maxItems === definition.minItems) {
         return resolveTuple(definition.items, definition.maxItems);