diff --git a/user/super/com/google/gwt/emul/java/lang/String.java b/user/super/com/google/gwt/emul/java/lang/String.java
index d023b3e..2ed5862 100644
--- a/user/super/com/google/gwt/emul/java/lang/String.java
+++ b/user/super/com/google/gwt/emul/java/lang/String.java
@@ -660,7 +660,7 @@
   @DoNotInline
   @Override
   public boolean equals(Object other) {
-    return (other instanceof String) && equals((String) other);
+    return (other instanceof String) && equals(unsafeCast(other));
   }
 
   // This a non-standard overload for faster code path when the target type is string. Note that
@@ -671,6 +671,11 @@
     return String(this) == other;
   }-*/;
 
+  // TODO(goktug): replace unsafeCast with a real cast when the compiler can optimize it.
+  static native String unsafeCast(Object string) /*-{
+    return string;
+  }-*/;
+
   public native boolean equalsIgnoreCase(String other) /*-{
     if (other == null) {
       return false;
diff --git a/user/super/com/google/gwt/emul/java/lang/System.java b/user/super/com/google/gwt/emul/java/lang/System.java
index e8a0631..c516276 100644
--- a/user/super/com/google/gwt/emul/java/lang/System.java
+++ b/user/super/com/google/gwt/emul/java/lang/System.java
@@ -112,7 +112,7 @@
 
   public static int identityHashCode(Object o) {
     return (o == null) ? 0 : (!(o instanceof String)) ? Impl.getHashCode(o)
-        : String.HashCache.getHashCode((String) o);
+        : String.HashCache.getHashCode(String.unsafeCast(o));
   }
 
   public static native void setErr(PrintStream err) /*-{
diff --git a/user/super/com/google/gwt/emul/java/util/AbstractHashMap.java b/user/super/com/google/gwt/emul/java/util/AbstractHashMap.java
index 140472b..3e86ee2 100644
--- a/user/super/com/google/gwt/emul/java/util/AbstractHashMap.java
+++ b/user/super/com/google/gwt/emul/java/util/AbstractHashMap.java
@@ -172,7 +172,7 @@
   @SpecializeMethod(params = {String.class}, target = "hasStringValue")
   @Override
   public boolean containsKey(Object key) {
-    return key instanceof String ? hasStringValue((String) key) : hasHashValue(key);
+    return key instanceof String ? hasStringValue(unsafeCast(key)) : hasHashValue(key);
   }
 
   @Override
@@ -188,19 +188,19 @@
   @SpecializeMethod(params = {String.class}, target = "getStringValue")
   @Override
   public V get(Object key) {
-    return key instanceof String ? getStringValue((String) key) : getHashValue(key);
+    return key instanceof String ? getStringValue(unsafeCast(key)) : getHashValue(key);
   }
 
   @SpecializeMethod(params = {String.class, Object.class}, target = "putStringValue")
   @Override
   public V put(K key, V value) {
-    return key instanceof String ? putStringValue((String) key, value) : putHashValue(key, value);
+    return key instanceof String ? putStringValue(unsafeCast(key), value) : putHashValue(key, value);
   }
 
   @SpecializeMethod(params = {String.class}, target = "removeStringValue")
   @Override
   public V remove(Object key) {
-    return key instanceof String ? removeStringValue((String) key) : removeHashValue(key);
+    return key instanceof String ? removeStringValue(unsafeCast(key)) : removeHashValue(key);
   }
 
   @Override
@@ -301,4 +301,9 @@
   protected V removeStringValue(String key) {
     return key == null ? removeHashValue(null) : stringMap.remove(key);
   }
+
+  // TODO(goktug): replace unsafeCast with a real cast when the compiler can optimize it.
+  static native String unsafeCast(Object string) /*-{
+    return string;
+  }-*/;
 }