diff --git a/Code/ObjectMapping/RKObjectLoader.m b/Code/ObjectMapping/RKObjectLoader.m
index 6f0fe37e..844e549e 100644
--- a/Code/ObjectMapping/RKObjectLoader.m
+++ b/Code/ObjectMapping/RKObjectLoader.m
@@ -297,7 +297,7 @@
 
 // Invoked just before request hits the network
 - (BOOL)prepareURLRequest {
-    if (self.sourceObject && (self.method == RKRequestMethodPOST || self.method == RKRequestMethodPUT)) {
+    if ((self.sourceObject && self.params == nil) && (self.method == RKRequestMethodPOST || self.method == RKRequestMethodPUT)) {
         NSAssert(self.serializationMapping, @"Cannot send an object to the remote");
         RKLogDebug(@"POST or PUT request for source object %@, serializing to MIME Type %@ for transport...", self.sourceObject, self.serializationMIMEType);
         RKObjectSerializer* serializer = [RKObjectSerializer serializerWithObject:self.sourceObject mapping:self.serializationMapping];
diff --git a/Specs/ObjectMapping/RKObjectManagerSpec.m b/Specs/ObjectMapping/RKObjectManagerSpec.m
index a64b0397..8b9370d0 100644
--- a/Specs/ObjectMapping/RKObjectManagerSpec.m
+++ b/Specs/ObjectMapping/RKObjectManagerSpec.m
@@ -311,4 +311,25 @@
     assertThat(responseLoader.response.request.resourcePath, is(equalTo(@"/humans/1")));    
 }
 
+- (void)itShouldLetYouOverloadTheParamsOnAnObjectLoaderRequest {
+    RKObjectManager* objectManager = RKSpecNewObjectManager();
+    RKObjectMapping* mapping = [RKObjectMapping mappingForClass:[RKObjectMapperSpecModel class]];
+    mapping.rootKeyPath = @"human";
+    [mapping mapAttributes:@"name", @"age", nil];
+    
+    RKSpecResponseLoader* responseLoader = [RKSpecResponseLoader responseLoader];
+    RKObjectMapperSpecModel* human = [[RKObjectMapperSpecModel new] autorelease];
+    human.name = @"Blake Watters";
+    human.age = [NSNumber numberWithInt:28];
+    NSDictionary *myParams = [NSDictionary dictionaryWithObject:@"bar" forKey:@"foo"];
+    RKObjectLoader* loader = [objectManager sendObject:human delegate:responseLoader block:^(RKObjectLoader* loader) {
+        loader.method = RKRequestMethodPOST;
+        loader.resourcePath = @"/humans/1";
+        loader.objectMapping = mapping;
+        loader.params = myParams;
+    }];
+    [responseLoader waitForResponse];
+    assertThat(loader.params, is(equalTo(myParams)));
+}
+
 @end