diff --git a/331_fine_tune_SAM_mito.ipynb b/331_fine_tune_SAM_mito.ipynb
index 6c4d70761..b85ad0d47 100644
--- a/331_fine_tune_SAM_mito.ipynb
+++ b/331_fine_tune_SAM_mito.ipynb
@@ -186,6 +186,7 @@
         "        for j in range(patches_img.shape[1]):\n",
         "\n",
         "            single_patch_img = patches_img[i,j,:,:]\n",
+        "            single_patch_img = np.stack((single_patch_img,) * 3, axis=-1)\n",
         "            all_img_patches.append(single_patch_img)\n",
         "\n",
         "images = np.array(all_img_patches)\n",
@@ -2312,4 +2313,4 @@
   },
   "nbformat": 4,
   "nbformat_minor": 0
-}
\ No newline at end of file
+}