diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index ea86b2b9b04..ee76698cd33 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -10867,6 +10867,8 @@ module ts {
                 checkGrammarSourceFile(node);
 
                 emitExtends = false;
+                emitDecorate = false;
+                emitParam = false;
                 potentialThisCollisions.length = 0;
 
                 forEach(node.statements, checkSourceElement);
diff --git a/tests/cases/conformance/decorators/class/decoratedClassFromExternalModule.ts b/tests/cases/conformance/decorators/class/decoratedClassFromExternalModule.ts
new file mode 100644
index 00000000000..cb622265b44
--- /dev/null
+++ b/tests/cases/conformance/decorators/class/decoratedClassFromExternalModule.ts
@@ -0,0 +1,9 @@
+// @target: es6
+// @Filename: decorated.ts
+function decorate() { }
+
+@decorate
+export default class Decorated { }
+
+// @Filename: undecorated.ts
+import Decorated from 'decorated';
\ No newline at end of file