diff --git a/src/main/resources/twilio-node/responseModel.mustache b/src/main/resources/twilio-node/responseModel.mustache
index 2c52b0118..5eb3d0e53 100644
--- a/src/main/resources/twilio-node/responseModel.mustache
+++ b/src/main/resources/twilio-node/responseModel.mustache
@@ -27,7 +27,7 @@ export class {{instanceName}} {
     {{/vars}}
 
     {{#instancePath}}
-    this._solution = { {{#instancePathParams}}{{paramName}}{{^vendorExtensions.x-is-parent-param}}: {{paramName}} || this.{{paramName}}{{#vendorExtensions.x-stringify}}.toString(){{/vendorExtensions.x-stringify}}{{/vendorExtensions.x-is-parent-param}}, {{/instancePathParams}} };
+    this._solution = { {{#instancePathParams}}{{paramName}}{{^vendorExtensions.x-is-parent-param}}: {{paramName}} || this.{{paramName}}{{#isNullable}}{{#vendorExtensions.x-stringify}}.toString(){{/vendorExtensions.x-stringify}}{{/isNullable}}{{/vendorExtensions.x-is-parent-param}}, {{/instancePathParams}} };
     {{/instancePath}}
   }