diff --git a/Tests/test_file_bmp.py b/Tests/test_file_bmp.py
index ec852c905..e857f881c 100644
--- a/Tests/test_file_bmp.py
+++ b/Tests/test_file_bmp.py
@@ -175,6 +175,7 @@ def test_rle8():
             with pytest.raises(ValueError):
                 im.load()
 
+
 def test_rle4():
     with Image.open("Tests/images/hopper_rle4.bmp") as im:
         assert_image_similar_tofile(im, "Tests/images/hopper_4bit.bmp", 12)
diff --git a/src/PIL/BmpImagePlugin.py b/src/PIL/BmpImagePlugin.py
index 107eb344d..d1517df27 100644
--- a/src/PIL/BmpImagePlugin.py
+++ b/src/PIL/BmpImagePlugin.py
@@ -348,7 +348,7 @@ class BmpRle4Decoder(ImageFile.PyDecoder):
                     # Too much data for row
                     num_pixels = max(0, self.state.xsize - x)
                 first_pixel = o8(byte[0] >> 4)
-                second_pixel = o8(byte[0] & 0x0f)
+                second_pixel = o8(byte[0] & 0x0F)
                 for index in range(num_pixels):
                     if index % 2 == 0:
                         data += first_pixel
@@ -379,11 +379,11 @@ class BmpRle4Decoder(ImageFile.PyDecoder):
                     for byte_read in bytes_read:
                         first_pixel = o8(byte_read >> 4)
                         data += first_pixel
-                        second_pixel = o8(byte_read & 0x0f)
+                        second_pixel = o8(byte_read & 0x0F)
                         data += second_pixel
                     if len(bytes_read) < total_bytes_to_read:
                         break
-                    x += byte[0] 
+                    x += byte[0]
 
                     # align to 16-bit word boundary
                     if self.fd.tell() % 2 != 0:
@@ -392,6 +392,7 @@ class BmpRle4Decoder(ImageFile.PyDecoder):
         self.set_as_raw(bytes(data), (rawmode, 0, self.args[-1]))
         return -1, 0
 
+
 # =============================================================================
 # Image plugin for the DIB format (BMP alias)
 # =============================================================================