diff --git a/dev/core/src/com/google/gwt/dev/jjs/ast/JNullType.java b/dev/core/src/com/google/gwt/dev/jjs/ast/JNullType.java
index 0bd8bff..c5ecc15 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/ast/JNullType.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/ast/JNullType.java
@@ -1,12 +1,12 @@
 /*
  * Copyright 2008 Google Inc.
- * 
+ *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
- * 
+ *
  * http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
@@ -62,4 +62,9 @@
   private Object readResolve() {
     return INSTANCE;
   }
+
+  @Override
+  public JNonNullType getNonNull() {
+    throw new UnsupportedOperationException();
+  }
 }
diff --git a/dev/core/src/com/google/gwt/dev/jjs/impl/MethodInliner.java b/dev/core/src/com/google/gwt/dev/jjs/impl/MethodInliner.java
index f991aaf..ae2ce51 100644
--- a/dev/core/src/com/google/gwt/dev/jjs/impl/MethodInliner.java
+++ b/dev/core/src/com/google/gwt/dev/jjs/impl/MethodInliner.java
@@ -1,12 +1,12 @@
 /*
  * Copyright 2007 Google Inc.
- * 
+ *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
  * use this file except in compliance with the License. You may obtain a copy of
  * the License at
- * 
+ *
  * http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
@@ -50,7 +50,7 @@
  * Inline methods that can be inlined. The current implementation limits the
  * methods that can be inlined to those that are composed of at most two
  * top-level expressions.
- * 
+ *
  * Future improvements will allow more complex methods to be inlined based on
  * the number of call sites, as well as adding support for more complex target
  * method expressions.
@@ -154,7 +154,7 @@
          * tighten an instance call to its static impl after the static impl had
          * already been inlined, this meant any "flow" type optimizer would have
          * to fake artifical flow from the instance method to the static impl.
-         * 
+         *
          * TODO: allow the inlining if we are the last remaining call site, and
          * prune the static impl? But it might tend to generate more code.
          */
@@ -213,7 +213,7 @@
      * Creates a JMultiExpression from a set of JExpressionStatements,
      * optionally terminated by a JReturnStatement. If the method doesn't match
      * this pattern, it returns <code>null</code>.
-     * 
+     *
      * If a method has a non-void return statement and can be represented as a
      * multi-expression, the output of the multi-expression will be the return
      * expression of the method. If the method is void, the output of the
@@ -289,7 +289,7 @@
        * Limit inlined methods to multiexpressions of length 2 for now. This
        * handles the simple { return JVariableRef; } or { expression; return
        * something; } cases.
-       * 
+       *
        * TODO: add an expression complexity analyzer.
        */
       if (targetExpr.getNumberOfExpressions() > 2) {
@@ -320,7 +320,7 @@
       /*
        * There are a different number of parameters than args - this is likely a
        * result of parameter pruning. Don't consider this call site a candidate.
-       * 
+       *
        * TODO: would this be possible in the trivial delegation case?
        */
       if (x.getTarget().getParams().size() != x.getArgs().size()) {
@@ -391,7 +391,7 @@
    * Verifies that all the parameters are referenced once and only once, not
    * within a conditionally-executing expression, and any before trouble some
    * expressions evaluate. Examples of troublesome expressions include:
-   * 
+   *
    * <ul>
    * <li>assignments to any variable</li>
    * <li>expressions that throw exceptions</li>
@@ -556,7 +556,11 @@
     } else {
       result = target;
     }
-    if ((!target.canBeNull())) {
+
+    // TODO(rluble): Replace a (non nullable) type by its JNonNullType version is always safe; but
+    // there already exists a pass that is responsible for making types tighten (TypeTightener)
+    // hence leaving this tightening unnecessary as it will be performed by a different pass.
+    if (!result.canBeNull()) {
       result = result.getNonNull();
     }
     return result;