diff --git a/Code/ObjectMapping/RKMappingOperation.m b/Code/ObjectMapping/RKMappingOperation.m
index cb17e279..293c85d4 100644
--- a/Code/ObjectMapping/RKMappingOperation.m
+++ b/Code/ObjectMapping/RKMappingOperation.m
@@ -98,7 +98,6 @@ BOOL RKObjectIsValueEqualToValue(id sourceValue, id destinationValue) {
     if (self) {
         self.sourceObject = sourceObject;
         self.destinationObject = destinationObject;
-        self.dataSource = [RKObjectMappingOperationDataSource new];
         self.mapping = objectOrDynamicMapping;
     }