diff --git a/src/main/java/org/jboss/netty/handler/execution/MemoryAwareThreadPoolExecutor.java b/src/main/java/org/jboss/netty/handler/execution/MemoryAwareThreadPoolExecutor.java
index 47d07a14db..bb38b21ef9 100644
--- a/src/main/java/org/jboss/netty/handler/execution/MemoryAwareThreadPoolExecutor.java
+++ b/src/main/java/org/jboss/netty/handler/execution/MemoryAwareThreadPoolExecutor.java
@@ -380,6 +380,9 @@ public class MemoryAwareThreadPoolExecutor extends ThreadPoolExecutor {
      * Returns the maximum total size of the queued events for this pool.
      */
     public long getMaxTotalMemorySize() {
+        if (totalLimiter == null) {
+            return 0;
+        }
         return totalLimiter.limit;
     }
 
diff --git a/src/test/java/org/jboss/netty/handler/execution/MemoryAwareThreadPoolExecutorTest.java b/src/test/java/org/jboss/netty/handler/execution/MemoryAwareThreadPoolExecutorTest.java
new file mode 100644
index 0000000000..54865d609f
--- /dev/null
+++ b/src/test/java/org/jboss/netty/handler/execution/MemoryAwareThreadPoolExecutorTest.java
@@ -0,0 +1,28 @@
+/*
+ * Copyright 2011 The Netty Project
+ *
+ * The Netty Project licenses this file to you 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
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */package org.jboss.netty.handler.execution;
+
+import static org.junit.Assert.*;
+import org.junit.Test;
+
+public class MemoryAwareThreadPoolExecutorTest {
+
+    // See https://github.com/netty/netty/issues/634
+    @Test
+    public void testNPEOnUnlimetedExecutor() {
+        MemoryAwareThreadPoolExecutor executor = new MemoryAwareThreadPoolExecutor(2, 0, 0);
+        assertEquals(0, executor.getMaxTotalMemorySize());
+    }
+}