diff --git a/Foundation/CPIndexSet.j b/Foundation/CPIndexSet.j
index 91855dc9b..bd3be224e 100644
--- a/Foundation/CPIndexSet.j
+++ b/Foundation/CPIndexSet.j
@@ -160,6 +160,13 @@
     return YES;
 }
 
+- (BOOL)isEqual:(id)anObject
+{
+    return  self === anObject ||
+            [anObject isKindOfClass:[self class]] &&
+            [self isEqualToIndexSet:anObject];
+}
+
 /*!
     Returns \c YES if the index set contains the specified index.
     @param anIndex the index to check for in the set
diff --git a/Tests/Foundation/CPIndexSetTest.j b/Tests/Foundation/CPIndexSetTest.j
index b244b8e1d..fed4726b9 100644
--- a/Tests/Foundation/CPIndexSetTest.j
+++ b/Tests/Foundation/CPIndexSetTest.j
@@ -252,12 +252,26 @@ function descriptionWithoutEntity(aString)
     var set1 = [CPIndexSet indexSetWithIndex:7];
     var set2 = [CPIndexSet indexSetWithIndex:7];
     var set3 = [CPIndexSet indexSetWithIndexesInRange:CPMakeRange(7, 2)];
-    
+
+    [self assertFalse:[set1 isEqualToIndexSet:nil]];
     [self assertTrue:[set1 isEqualToIndexSet:set2]];
     [self assertTrue:[set1 isEqualToIndexSet:set1]];
     [self assertFalse:[set1 isEqualToIndexSet:set3]];
 }
 
+- (void)testIsEqual
+{
+    var set1 = [CPIndexSet indexSetWithIndex:7];
+    var set2 = [CPIndexSet indexSetWithIndex:7];
+    var set3 = [CPIndexSet indexSetWithIndexesInRange:CPMakeRange(7, 2)];
+
+    [self assertFalse:[set1 isEqual:nil]];
+    [self assertFalse:[set1 isEqual:7]];
+    [self assertTrue:[set1 isEqual:set2]];
+    [self assertTrue:[set1 isEqual:set1]];
+    [self assertFalse:[set1 isEqual:set3]];
+}
+
 - (void)testCount
 {
     var set = [CPIndexSet indexSetWithIndexesInRange:CPMakeRange(7, 2)];