diff --git a/src/main/java/com/google/gwtorm/client/IntKey.java b/src/main/java/com/google/gwtorm/client/IntKey.java
index 7dcfbf7..cba56dd 100644
--- a/src/main/java/com/google/gwtorm/client/IntKey.java
+++ b/src/main/java/com/google/gwtorm/client/IntKey.java
@@ -54,14 +54,7 @@
     }
 
     final IntKey<P> q = cast(b);
-    if (get() == q.get()) {
-      if (getParentKey() != null) {
-        return getParentKey().equals(q.getParentKey());
-      }
-      return true;
-    }
-
-    return false;
+    return get() == q.get() && KeyUtil.eq(getParentKey(), q.getParentKey());
   }
 
   @Override
diff --git a/src/main/java/com/google/gwtorm/client/KeyUtil.java b/src/main/java/com/google/gwtorm/client/KeyUtil.java
new file mode 100644
index 0000000..acecb10
--- /dev/null
+++ b/src/main/java/com/google/gwtorm/client/KeyUtil.java
@@ -0,0 +1,30 @@
+// 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 License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.gwtorm.client;
+
+class KeyUtil {
+  static <T extends Key<?>> boolean eq(final T a, final T b) {
+    if (a == b) {
+      return true;
+    }
+    if (a == null || b == null) {
+      return false;
+    }
+    return a.equals(b);
+  }
+
+  private KeyUtil() {
+  }
+}
diff --git a/src/main/java/com/google/gwtorm/client/LongKey.java b/src/main/java/com/google/gwtorm/client/LongKey.java
index 2fc5d6b..3741e2c 100644
--- a/src/main/java/com/google/gwtorm/client/LongKey.java
+++ b/src/main/java/com/google/gwtorm/client/LongKey.java
@@ -54,14 +54,7 @@
     }
 
     final LongKey<P> q = cast(b);
-    if (get() == q.get()) {
-      if (getParentKey() != null) {
-        return getParentKey().equals(q.getParentKey());
-      }
-      return true;
-    }
-
-    return false;
+    return get() == q.get() && KeyUtil.eq(getParentKey(), q.getParentKey());
   }
 
   @Override
diff --git a/src/main/java/com/google/gwtorm/client/ShortKey.java b/src/main/java/com/google/gwtorm/client/ShortKey.java
index 8919715..937c3f3 100644
--- a/src/main/java/com/google/gwtorm/client/ShortKey.java
+++ b/src/main/java/com/google/gwtorm/client/ShortKey.java
@@ -55,14 +55,7 @@
     }
 
     final ShortKey<P> q = cast(b);
-    if (get() == q.get()) {
-      if (getParentKey() != null) {
-        return getParentKey().equals(q.getParentKey());
-      }
-      return true;
-    }
-
-    return false;
+    return get() == q.get() && KeyUtil.eq(getParentKey(), q.getParentKey());
   }
 
   @Override
diff --git a/src/main/java/com/google/gwtorm/client/StringKey.java b/src/main/java/com/google/gwtorm/client/StringKey.java
index 427c8ad..20172c4 100644
--- a/src/main/java/com/google/gwtorm/client/StringKey.java
+++ b/src/main/java/com/google/gwtorm/client/StringKey.java
@@ -55,14 +55,8 @@
     }
 
     final StringKey<P> q = cast(b);
-    if (get().equals(q.get())) {
-      if (getParentKey() != null) {
-        return getParentKey().equals(q.getParentKey());
-      }
-      return true;
-    }
-
-    return false;
+    return get().equals(q.get())
+        && KeyUtil.eq(getParentKey(), q.getParentKey());
   }
 
   @Override