diff --git a/Code/Network/RKObjectManager.m b/Code/Network/RKObjectManager.m
index 82058e10..a2e0ef55 100644
--- a/Code/Network/RKObjectManager.m
+++ b/Code/Network/RKObjectManager.m
@@ -407,6 +407,7 @@ static NSString *RKMIMETypeFromAFHTTPClientParameterEncoding(AFHTTPClientParamet
           success:(void (^)(RKObjectRequestOperation *operation, RKMappingResult *mappingResult))success
           failure:(void (^)(RKObjectRequestOperation *operation, NSError *error))failure
 {
+    NSParameterAssert(object);
     RKObjectRequestOperation *operation = [self appropriateObjectRequestOperationWithObject:object method:RKRequestMethodGET path:path parameters:parameters];
     [operation setCompletionBlockWithSuccess:success failure:failure];
     [self enqueueObjectRequestOperation:operation];
@@ -418,6 +419,7 @@ static NSString *RKMIMETypeFromAFHTTPClientParameterEncoding(AFHTTPClientParamet
            success:(void (^)(RKObjectRequestOperation *operation, RKMappingResult *mappingResult))success
            failure:(void (^)(RKObjectRequestOperation *operation, NSError *error))failure
 {
+    NSParameterAssert(object);
     RKObjectRequestOperation *operation = [self appropriateObjectRequestOperationWithObject:object method:RKRequestMethodPOST path:path parameters:parameters];
     [operation setCompletionBlockWithSuccess:success failure:failure];
     [self enqueueObjectRequestOperation:operation];
@@ -429,6 +431,7 @@ static NSString *RKMIMETypeFromAFHTTPClientParameterEncoding(AFHTTPClientParamet
           success:(void (^)(RKObjectRequestOperation *operation, RKMappingResult *mappingResult))success
           failure:(void (^)(RKObjectRequestOperation *operation, NSError *error))failure
 {
+    NSParameterAssert(object);
     RKObjectRequestOperation *operation = [self appropriateObjectRequestOperationWithObject:object method:RKRequestMethodPUT path:path parameters:parameters];
     [operation setCompletionBlockWithSuccess:success failure:failure];
     [self enqueueObjectRequestOperation:operation];
@@ -440,6 +443,7 @@ static NSString *RKMIMETypeFromAFHTTPClientParameterEncoding(AFHTTPClientParamet
             success:(void (^)(RKObjectRequestOperation *operation, RKMappingResult *mappingResult))success
             failure:(void (^)(RKObjectRequestOperation *operation, NSError *error))failure
 {
+    NSParameterAssert(object);
     RKObjectRequestOperation *operation = [self appropriateObjectRequestOperationWithObject:object method:RKRequestMethodPATCH path:path parameters:parameters];
     [operation setCompletionBlockWithSuccess:success failure:failure];
     [self enqueueObjectRequestOperation:operation];
@@ -451,6 +455,7 @@ static NSString *RKMIMETypeFromAFHTTPClientParameterEncoding(AFHTTPClientParamet
              success:(void (^)(RKObjectRequestOperation *operation, RKMappingResult *mappingResult))success
              failure:(void (^)(RKObjectRequestOperation *operation, NSError *error))failure
 {
+    NSParameterAssert(object);
     RKObjectRequestOperation *operation = [self appropriateObjectRequestOperationWithObject:object method:RKRequestMethodDELETE path:path parameters:parameters];
     [operation setCompletionBlockWithSuccess:success failure:failure];
     [self enqueueObjectRequestOperation:operation];