diff --git a/Code/Network/RKObjectManager.m b/Code/Network/RKObjectManager.m
index 2322491c..82058e10 100644
--- a/Code/Network/RKObjectManager.m
+++ b/Code/Network/RKObjectManager.m
@@ -68,9 +68,14 @@ static NSArray *RKFilteredArrayOfResponseDescriptorsMatchingPath(NSArray *respon
  */
 static RKRequestDescriptor *RKRequestDescriptorFromArrayMatchingObject(NSArray *requestDescriptors, id object)
 {
-    for (RKRequestDescriptor *requestDescriptor in requestDescriptors) {
-        if ([requestDescriptor matchesObject:object]) return requestDescriptor;
-    }
+    Class searchClass = [object class];
+    do {
+        for (RKRequestDescriptor *requestDescriptor in requestDescriptors) {
+            if ([requestDescriptor.objectClass isEqual:searchClass]) return requestDescriptor;
+        }
+        searchClass = [searchClass superclass];
+    } while (searchClass);
+    
     return nil;
 }
 
@@ -459,7 +464,11 @@ static NSString *RKMIMETypeFromAFHTTPClientParameterEncoding(AFHTTPClientParamet
 - (void)addRequestDescriptor:(RKRequestDescriptor *)requestDescriptor
 {
     NSParameterAssert(requestDescriptor);
+    if ([self.requestDescriptors containsObject:requestDescriptor]) return;
     NSAssert([requestDescriptor isKindOfClass:[RKRequestDescriptor class]], @"Expected an object of type RKRequestDescriptor, got '%@'", [requestDescriptor class]);
+    [self.requestDescriptors enumerateObjectsUsingBlock:^(RKRequestDescriptor *registeredDescriptor, NSUInteger idx, BOOL *stop) {
+        NSAssert(![registeredDescriptor.objectClass isEqual:requestDescriptor.objectClass], @"Cannot add a request descriptor for the same object class as an existing request descriptor.");
+    }];
     [self.mutableRequestDescriptors addObject:requestDescriptor];
 }
 
diff --git a/Tests/Logic/ObjectMapping/RKObjectManagerTest.m b/Tests/Logic/ObjectMapping/RKObjectManagerTest.m
index 609da028..ba6d97c7 100644
--- a/Tests/Logic/ObjectMapping/RKObjectManagerTest.m
+++ b/Tests/Logic/ObjectMapping/RKObjectManagerTest.m
@@ -26,6 +26,12 @@
 #import "RKCat.h"
 #import "RKObjectMapperTestModel.h"
 
+@interface RKSubclassedTestModel : RKObjectMapperTestModel
+@end
+
+@implementation RKSubclassedTestModel
+@end
+
 @interface RKTestAFHTTPClient : AFHTTPClient
 @end
 
@@ -480,6 +486,48 @@
     });
 }
 
+- (void)testThatAttemptingToAddARequestDescriptorThatOverlapsAnExistingEntryGeneratesAnError
+{
+    RKObjectMapping *mapping = [RKObjectMapping requestMapping];
+    RKRequestDescriptor *requestDesriptor1 = [RKRequestDescriptor requestDescriptorWithMapping:mapping objectClass:[RKCat class] rootKeyPath:nil];
+    RKRequestDescriptor *requestDesriptor2 = [RKRequestDescriptor requestDescriptorWithMapping:mapping objectClass:[RKCat class] rootKeyPath:@"cat"];
+    RKObjectManager *objectManager = [RKTestFactory objectManager];
+    [objectManager addRequestDescriptor:requestDesriptor1];
+    
+    NSException *caughtException = nil;
+    @try {
+        [objectManager addRequestDescriptor:requestDesriptor2];
+    }
+    @catch (NSException *exception) {
+        caughtException = exception;
+    }
+    @finally {
+        expect(caughtException).notTo.beNil();
+    }
+}
+
+- (void)testThatRegisteringARequestDescriptorForASubclassSecondWillMatchAppropriately
+{
+    RKObjectMapping *mapping1 = [RKObjectMapping requestMapping];
+    [mapping1 addAttributeMappingsFromArray:@[ @"name" ]];
+    RKObjectMapping *mapping2 = [RKObjectMapping requestMapping];
+    [mapping2 addAttributeMappingsFromArray:@[ @"age" ]];
+    
+    RKRequestDescriptor *requestDesriptor1 = [RKRequestDescriptor requestDescriptorWithMapping:mapping1 objectClass:[RKObjectMapperTestModel class] rootKeyPath:nil];
+    RKRequestDescriptor *requestDesriptor2 = [RKRequestDescriptor requestDescriptorWithMapping:mapping2 objectClass:[RKSubclassedTestModel class] rootKeyPath:@"subclassed"];
+    RKObjectManager *objectManager = [RKTestFactory objectManager];
+    objectManager.requestSerializationMIMEType = RKMIMETypeJSON;
+    [objectManager addRequestDescriptor:requestDesriptor1];
+    [objectManager addRequestDescriptor:requestDesriptor2];
+    
+    RKSubclassedTestModel *model = [RKSubclassedTestModel new];
+    model.name = @"Blake";
+    model.age = @30;
+    NSURLRequest *request = [objectManager requestWithObject:model method:RKRequestMethodPOST path:@"/path" parameters:nil];
+    NSDictionary *dictionary = [NSJSONSerialization JSONObjectWithData:request.HTTPBody options:0 error:nil];
+    expect(dictionary).to.equal(@{ @"subclassed": @{ @"age": @(30) } });
+}
+
 //- (void)testShouldHandleConnectionFailures
 //{
 //    NSString *localBaseURL = [NSString stringWithFormat:@"http://127.0.0.1:3001"];
diff --git a/Tests/Models/RKObjectMapperTestModel.h b/Tests/Models/RKObjectMapperTestModel.h
index f3f4595b..b3785653 100644
--- a/Tests/Models/RKObjectMapperTestModel.h
+++ b/Tests/Models/RKObjectMapperTestModel.h
@@ -21,11 +21,7 @@
 
 #import <Foundation/Foundation.h>
 
-@interface RKObjectMapperTestModel : NSObject {
-    NSString *_name;
-    NSNumber *_age;
-    NSDate *_createdAt;
-}
+@interface RKObjectMapperTestModel : NSObject
 
 @property (nonatomic, strong) NSString *name;
 @property (nonatomic, strong) NSNumber *age;
diff --git a/Tests/Models/RKObjectMapperTestModel.m b/Tests/Models/RKObjectMapperTestModel.m
index 8029c569..8ee979fd 100644
--- a/Tests/Models/RKObjectMapperTestModel.m
+++ b/Tests/Models/RKObjectMapperTestModel.m
@@ -21,9 +21,4 @@
 #import "RKObjectMapperTestModel.h"
 
 @implementation RKObjectMapperTestModel
-
-@synthesize name = _name;
-@synthesize age = _age;
-@synthesize createdAt = _createdAt;
-
 @end