diff --git a/AFNetworking/AFHTTPClient.m b/AFNetworking/AFHTTPClient.m
index b913da1..354aa21 100644
--- a/AFNetworking/AFHTTPClient.m
+++ b/AFNetworking/AFHTTPClient.m
@@ -509,7 +509,9 @@ static void AFNetworkReachabilityReleaseCallback(const void *info) {
             data = [[component.value description] dataUsingEncoding:self.stringEncoding];
         }
         
-        [formData appendPartWithFormData:data name:[component.key description]];
+        if (data) {
+            [formData appendPartWithFormData:data name:[component.key description]];
+        }
     }
 
     if (block) {