diff --git a/customPatchMatch.py b/customPatchMatch.py
index 3ebfd91..2cf3894 100644
--- a/customPatchMatch.py
+++ b/customPatchMatch.py
@@ -7,7 +7,8 @@ import numpy as np
 def doPatchMatch(img,x1,y1,x2,y2,patchSize=17):
 
     def dist(patchValue1,patchValue2):
-        return np.sum((patchValue1 - patchValue2) ** 2)
+        mask = np.all(patchValue1 == [-1, -1, -1, -1], axis=-1)
+        return np.sum((patchValue1[~mask] - patchValue2[~mask]) ** 2)
 
     def patchToValue(patch):
         return img[patch[0][1]:patch[len(patch)-1][1], patch[0][0]:patch[len(patch)-1][0]]