diff --git a/mu-trees/addon/module-registries/requirejs.js b/mu-trees/addon/module-registries/requirejs.js
index 748f46f0..7c4eefaa 100644
--- a/mu-trees/addon/module-registries/requirejs.js
+++ b/mu-trees/addon/module-registries/requirejs.js
@@ -61,8 +61,8 @@ export default class RequireJSRegistry {
   }
 
   _checkDefaultType(specifier) {
-    let {defaultType} = this._config.collections[specifier.collection];
-    return defaultType && defaultType === specifier.type;
+    let collection = this._config.collections[specifier.collection];
+    return collection && collection.defaultType && collection.defaultType === specifier.type;
   }
 
   has(specifierString) {