diff --git a/wisp/ops/image/metrics.py b/wisp/ops/image/metrics.py
index 0f971c7..1454ea0 100644
--- a/wisp/ops/image/metrics.py
+++ b/wisp/ops/image/metrics.py
@@ -87,4 +87,5 @@ def ssim(rgb, gts):
         multichannel=True,
         data_range=1,
         gaussian_weights=True,
-        sigma=1.5)
+        sigma=1.5,
+        channel_axis=-1)