diff --git a/PCV/localdescriptors/harris.py b/PCV/localdescriptors/harris.py
index e91456c..ebfd107 100644
--- a/PCV/localdescriptors/harris.py
+++ b/PCV/localdescriptors/harris.py
@@ -22,7 +22,7 @@ def compute_harris_response(im,sigma=3):
     Wdet = Wxx*Wyy - Wxy**2
     Wtr = Wxx + Wyy
     
-    return Wdet / Wtr
+    return Wdet / (Wtr*Wtr)
    
     
 def get_harris_points(harrisim,min_dist=10,threshold=0.1):
diff --git a/pcv_book/harris.py b/pcv_book/harris.py
index e91456c..ebfd107 100644
--- a/pcv_book/harris.py
+++ b/pcv_book/harris.py
@@ -22,7 +22,7 @@ def compute_harris_response(im,sigma=3):
     Wdet = Wxx*Wyy - Wxy**2
     Wtr = Wxx + Wyy
     
-    return Wdet / Wtr
+    return Wdet / (Wtr*Wtr)
    
     
 def get_harris_points(harrisim,min_dist=10,threshold=0.1):