diff --git a/Code/CoreData/RKFetchRequestManagedObjectCache.m b/Code/CoreData/RKFetchRequestManagedObjectCache.m
index aa351c0865..1effc6f778 100644
--- a/Code/CoreData/RKFetchRequestManagedObjectCache.m
+++ b/Code/CoreData/RKFetchRequestManagedObjectCache.m
@@ -17,13 +17,19 @@
 #define RKLogComponent RKlcl_cRestKitCoreData
 
 /*
- NOTE: At the moment this cache key assume that the structure of the values for each key in the `attributeValues` in constant
- i.e. if you have `userID`, it will always be a single value, or `userIDs` will always be an array.
- It will need to be reimplemented if changes in attribute values occur during the life of a single cache
+ This function computes a cache key given a dictionary of attribute values. Each attribute name is used as a fragment within the aggregate cache key. A suffix qualifier is appended that differentiates singular vs. collection attribute values so that '==' and 'IN' predicates are computed appropriately.
  */
-static NSString *RKPredicateCacheKeyForAttributes(NSArray *attributeNames)
+static NSString *RKPredicateCacheKeyForAttributeValues(NSDictionary *attributesValues)
 {
-    return [[attributeNames sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)] componentsJoinedByString:@":"];
+    NSArray *sortedKeys = [[attributesValues allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
+    NSMutableArray *keyFragments = [NSMutableArray array];
+    for (NSString *attributeName in sortedKeys) {
+        id value = [attributesValues objectForKey:attributeName];
+        char suffix = ([value respondsToSelector:@selector(count)]) ? '+' : '.';
+        NSString *attributeKey = [NSString stringWithFormat:@"%@%c", attributeName, suffix];
+        [keyFragments addObject:attributeKey];
+    }
+    return [keyFragments componentsJoinedByString:@":"];
 }
 
 // NOTE: We build a dynamic format string here because `NSCompoundPredicate` does not support use of substiution variables
@@ -65,7 +71,7 @@ - (NSSet *)managedObjectsWithEntity:(NSEntityDescription *)entity
     NSAssert(attributeValues, @"Cannot retrieve cached objects without attribute values to identify them with.");
     NSAssert(managedObjectContext, @"Cannot find existing managed object with a nil context");
     
-    NSString *predicateCacheKey = RKPredicateCacheKeyForAttributes([attributeValues allKeys]);
+    NSString *predicateCacheKey = RKPredicateCacheKeyForAttributeValues(attributeValues);
     NSPredicate *substitutionPredicate = [self.predicateCache objectForKey:predicateCacheKey];
     if (! substitutionPredicate) {
         substitutionPredicate = RKPredicateWithSubsitutionVariablesForAttributeValues(attributeValues);
diff --git a/Tests/Logic/CoreData/RKFetchRequestMappingCacheTest.m b/Tests/Logic/CoreData/RKFetchRequestMappingCacheTest.m
index b9c31b265c..0297a34b60 100644
--- a/Tests/Logic/CoreData/RKFetchRequestMappingCacheTest.m
+++ b/Tests/Logic/CoreData/RKFetchRequestMappingCacheTest.m
@@ -16,6 +16,16 @@ @interface RKFetchRequestMappingCacheTest : RKTestCase
 
 @implementation RKFetchRequestMappingCacheTest
 
+- (void)setUp
+{
+    [RKTestFactory setUp];
+}
+
+- (void)tearDown
+{
+    [RKTestFactory tearDown];
+}
+
 - (void)testFetchRequestMappingCacheReturnsObjectsWithNumericPrimaryKey
 {
     // RKCat entity. Integer prinmary key.
@@ -57,4 +67,43 @@ - (void)testFetchRequestMappingCacheReturnsObjectsWithStringPrimaryKey
     expect(managedObjects).to.equal(birthdays);
 }
 
+- (void)testThatCacheCanHandleSwitchingBetweenSingularAndPluralAttributeValues
+{
+    // RKEvent entity. String primary key
+    RKManagedObjectStore *managedObjectStore = [RKTestFactory managedObjectStore];
+    RKFetchRequestManagedObjectCache *cache = [RKFetchRequestManagedObjectCache new];
+    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Event" inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    RKEntityMapping *mapping = [RKEntityMapping mappingForEntityForName:@"Event" inManagedObjectStore:managedObjectStore];
+    mapping.identificationAttributes = @[ @"eventID" ];
+    
+    RKEvent *event1 = [NSEntityDescription insertNewObjectForEntityForName:@"Event" inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    event1.eventID = @"e-1234-a8-b12";
+    
+    RKEvent *event2 = [NSEntityDescription insertNewObjectForEntityForName:@"Event" inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    event2.eventID = @"ff-1234-a8-b12";
+    
+    [managedObjectStore.persistentStoreManagedObjectContext save:nil];
+    
+    NSSet *managedObjects = [cache managedObjectsWithEntity:entity
+                                            attributeValues:@{ @"eventID": @[ event1.eventID, event2.eventID ] }
+                                     inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    NSSet *events = [NSSet setWithObjects:event1, event2, nil];
+    expect(managedObjects).to.haveCountOf(2);
+    expect(managedObjects).to.equal(events);
+    
+    managedObjects = [cache managedObjectsWithEntity:entity
+                                     attributeValues:@{ @"eventID": event1.eventID }
+                              inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    events = [NSSet setWithObject:event1];
+    expect(managedObjects).to.haveCountOf(1);
+    expect(managedObjects).to.equal(events);
+    
+    managedObjects = [cache managedObjectsWithEntity:entity
+                                     attributeValues:@{ @"eventID": @[ event1.eventID ] }
+                              inManagedObjectContext:managedObjectStore.persistentStoreManagedObjectContext];
+    events = [NSSet setWithObject:event1];
+    expect(managedObjects).to.haveCountOf(1);
+    expect(managedObjects).to.equal(events);
+}
+
 @end