diff --git a/classpath/java/util/Collections.java b/classpath/java/util/Collections.java
index 134c481322..d2391d7435 100644
--- a/classpath/java/util/Collections.java
+++ b/classpath/java/util/Collections.java
@@ -143,10 +143,10 @@ public class Collections {
     public void clear() {
       synchronized (lock) { map.clear(); }
     }
-    public boolean containsKey(K key) {
+    public boolean containsKey(Object key) {
       synchronized (lock) { return map.containsKey(key); }
     }
-    public boolean containsValue(V value) {
+    public boolean containsValue(Object value) {
       synchronized (lock) { return map.containsValue(value); }
     }
     public Set<java.util.Map.Entry<K, V>> entrySet() {
diff --git a/classpath/java/util/HashMap.java b/classpath/java/util/HashMap.java
index 43ee2e8148..913f58b696 100644
--- a/classpath/java/util/HashMap.java
+++ b/classpath/java/util/HashMap.java
@@ -158,12 +158,12 @@ public class HashMap<K, V> implements Map<K, V> {
     return c;
   }
 
-  public boolean containsKey(K key) {
-    return find(key) != null;
+  public boolean containsKey(Object key) {
+    return find((K)key) != null;
   }
 
-  public boolean containsValue(V value) {
-    return values().contains(value);
+  public boolean containsValue(Object value) {
+    return values().contains((V)value);
   }
 
   public V get(K key) {
diff --git a/classpath/java/util/Hashtable.java b/classpath/java/util/Hashtable.java
index 8ae75941a3..b08b4c3b67 100644
--- a/classpath/java/util/Hashtable.java
+++ b/classpath/java/util/Hashtable.java
@@ -40,11 +40,11 @@ public class Hashtable<K, V> implements Map<K, V> {
     return map.size();
   }
 
-  public synchronized boolean containsKey(K key) {
+  public synchronized boolean containsKey(Object key) {
     return map.containsKey(key);
   }
 
-  public synchronized boolean containsValue(V value) {
+  public synchronized boolean containsValue(Object value) {
     return map.containsValue(value);
   }
 
diff --git a/classpath/java/util/IdentityHashMap.java b/classpath/java/util/IdentityHashMap.java
index 7a86c5a192..123c26990e 100644
--- a/classpath/java/util/IdentityHashMap.java
+++ b/classpath/java/util/IdentityHashMap.java
@@ -29,11 +29,11 @@ public class IdentityHashMap<K, V> implements Map<K, V> {
     return map.size();
   }
 
-  public boolean containsKey(K key) {
+  public boolean containsKey(Object key) {
     return map.containsKey(key);
   }
 
-  public boolean containsValue(V value) {
+  public boolean containsValue(Object value) {
     return map.containsValue(value);
   }
 
diff --git a/classpath/java/util/Map.java b/classpath/java/util/Map.java
index 0b5fa550b2..bdb02e52c4 100644
--- a/classpath/java/util/Map.java
+++ b/classpath/java/util/Map.java
@@ -15,9 +15,9 @@ public interface Map<K, V> {
 
   public int size();
 
-  public boolean containsKey(K key);
+  public boolean containsKey(Object key);
 
-  public boolean containsValue(V value);
+  public boolean containsValue(Object value);
 
   public V get(K key);
 
diff --git a/classpath/java/util/WeakHashMap.java b/classpath/java/util/WeakHashMap.java
index 1618d58907..8a8da9c1c0 100644
--- a/classpath/java/util/WeakHashMap.java
+++ b/classpath/java/util/WeakHashMap.java
@@ -44,12 +44,12 @@ public class WeakHashMap<K, V> implements Map<K, V> {
     return map.size();
   }
 
-  public boolean containsKey(K key) {
+  public boolean containsKey(Object key) {
     poll();
     return map.containsKey(key);
   }
 
-  public boolean containsValue(V value) {
+  public boolean containsValue(Object  value) {
     poll();
     return map.containsValue(value);
   }