diff --git a/sdk/lib/_internal/compiler/implementation/inferrer/simple_types_inferrer.dart b/sdk/lib/_internal/compiler/implementation/inferrer/simple_types_inferrer.dart
index 3d0941d..1966d85 100644
--- a/sdk/lib/_internal/compiler/implementation/inferrer/simple_types_inferrer.dart
+++ b/sdk/lib/_internal/compiler/implementation/inferrer/simple_types_inferrer.dart
@@ -573,6 +573,11 @@
   }
 
   T visitFunctionExpression(ast.FunctionExpression node) {
+    // We loose track of [this] in closures (see issue 20840). To be on
+    // the safe side, we mark [this] as exposed here. We could do better by
+    // analyzing the closure.
+    // TODO(herhut): Analyze whether closure exposes this.
+    isThisExposed = true;
     LocalFunctionElement element = elements.getFunctionDefinition(node);
     // We don't put the closure in the work queue of the
     // inferrer, because it will share information with its enclosing
diff --git a/tests/language/regress_20840_test.dart b/tests/language/regress_20840_test.dart
new file mode 100644
index 0000000..117fa0e
--- /dev/null
+++ b/tests/language/regress_20840_test.dart
@@ -0,0 +1,25 @@
+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+// Regression test for issue 20840.
+
+class SomeClass {
+  Object someField;
+
+  SomeClass() {
+    [1].forEach((o) => someMethod());
+    someField = new Object();
+  }
+
+  void someMethod() {
+    if (someField != null) {
+      throw "FAIL";
+    }
+  }
+}
+
+void main() {
+  new SomeClass();
+}
+
diff --git a/tools/VERSION b/tools/VERSION
index 61efb2e..e28b058 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -26,6 +26,6 @@
 CHANNEL stable
 MAJOR 1
 MINOR 6
-PATCH 1
+PATCH 2
 PRERELEASE 0
 PRERELEASE_PATCH 0