diff --git a/modules/facade/src/lang.es6 b/modules/facade/src/lang.es6
index 9872c3f35e..62c66aef1b 100644
--- a/modules/facade/src/lang.es6
+++ b/modules/facade/src/lang.es6
@@ -3,6 +3,10 @@ import {assert} from 'rtts_assert/rtts_assert';
 export var Type = Function;
 export var Math = window.Math;
 
+// global assert support, as Dart has it...
+// TODO: `assert` calls need to be removed in production code!
+window.assert = assert;
+
 export class FIELD {
   constructor(definition) {
     this.definition = definition;