diff --git a/PIL/Image.py b/PIL/Image.py
index cf5c4f477..43748ee76 100644
--- a/PIL/Image.py
+++ b/PIL/Image.py
@@ -1150,7 +1150,7 @@ class Image:
         if isinstance(lut, ImagePointHandler):
             return lut.point(self)
 
-        if not isinstance(lut, collections.Sequence):
+        if callable(lut):
             # if it isn't a list, it should be a function
             if self.mode in ("I", "I;16", "F"):
                 # check if the function can be used with point_transform
diff --git a/Tests/test_numpy.py b/Tests/test_numpy.py
index 61b3cf480..85596047b 100644
--- a/Tests/test_numpy.py
+++ b/Tests/test_numpy.py
@@ -106,3 +106,15 @@ def test_to_array():
     for mode in modes:
         assert_no_exception(lambda: _to_array(*mode))
 
+
+def test_point_lut():
+    # see https://github.com/python-imaging/Pillow/issues/439
+    
+    data = list(range(256))*3
+    lut = numpy.array(data, dtype='uint8')
+
+    im = lena()
+
+    assert_no_exception(lambda: im.point(lut))
+    
+