diff --git a/fawkes/detect_faces.py b/fawkes/detect_faces.py
index 9d6f317..5d4bf23 100644
--- a/fawkes/detect_faces.py
+++ b/fawkes/detect_faces.py
@@ -704,7 +704,7 @@ def nms(boxes, threshold, method):
         w = np.maximum(0.0, xx2 - xx1 + 1)
         h = np.maximum(0.0, yy2 - yy1 + 1)
         inter = w * h
-        if method is 'Min':
+        if method == 'Min':
             o = inter / np.minimum(area[i], area[idx])
         else:
             o = inter / (area[i] + area[idx] - inter)