diff --git a/mmflow/models/utils/res_layer.py b/mmflow/models/utils/res_layer.py
index 14b60d46..6e8ff86a 100644
--- a/mmflow/models/utils/res_layer.py
+++ b/mmflow/models/utils/res_layer.py
@@ -78,7 +78,7 @@ def _inner_forward(x):
             if self.downsample is not None:
                 identity = self.downsample(x)
 
-            out += identity
+            out = out + identity
 
             return out
 
@@ -288,7 +288,7 @@ def _inner_forward(x):
             if self.downsample is not None:
                 identity = self.downsample(x)
 
-            out += identity
+            out = out + identity
 
             return out