diff --git a/src/main/java/org/jboss/netty/util/ConcurrentHashMap.java b/src/main/java/org/jboss/netty/util/ConcurrentHashMap.java
index 86f8281b87..14796e9e32 100644
--- a/src/main/java/org/jboss/netty/util/ConcurrentHashMap.java
+++ b/src/main/java/org/jboss/netty/util/ConcurrentHashMap.java
@@ -1131,6 +1131,7 @@ public final class ConcurrentHashMap<K, V> extends AbstractMap<K, V>
             currentTable = null;
             nextEntry = null;
             lastReturned = null;
+            currentKey = null;
             advance();
         }
 
diff --git a/src/main/java/org/jboss/netty/util/ConcurrentIdentityHashMap.java b/src/main/java/org/jboss/netty/util/ConcurrentIdentityHashMap.java
index 27c957b5bd..934af43a24 100644
--- a/src/main/java/org/jboss/netty/util/ConcurrentIdentityHashMap.java
+++ b/src/main/java/org/jboss/netty/util/ConcurrentIdentityHashMap.java
@@ -1131,6 +1131,7 @@ public final class ConcurrentIdentityHashMap<K, V> extends AbstractMap<K, V>
             currentTable = null;
             nextEntry = null;
             lastReturned = null;
+            currentKey = null;
             advance();
         }
 
diff --git a/src/main/java/org/jboss/netty/util/ConcurrentIdentityWeakHashMap.java b/src/main/java/org/jboss/netty/util/ConcurrentIdentityWeakHashMap.java
index 0fc5293b38..01fedc76ed 100644
--- a/src/main/java/org/jboss/netty/util/ConcurrentIdentityWeakHashMap.java
+++ b/src/main/java/org/jboss/netty/util/ConcurrentIdentityWeakHashMap.java
@@ -1213,6 +1213,7 @@ public final class ConcurrentIdentityWeakHashMap<K, V> extends AbstractMap<K, V>
             currentTable = null;
             nextEntry = null;
             lastReturned = null;
+            currentKey = null;
             advance();
         }