diff --git a/Tests/images/dxt5-colorblock-alpha-issue-4142.dds b/Tests/images/dxt5-colorblock-alpha-issue-4142.dds
new file mode 100644
index 000000000..905527ead
Binary files /dev/null and b/Tests/images/dxt5-colorblock-alpha-issue-4142.dds differ
diff --git a/Tests/test_file_dds.py b/Tests/test_file_dds.py
index 1cd7a1be7..5651c2e4d 100644
--- a/Tests/test_file_dds.py
+++ b/Tests/test_file_dds.py
@@ -190,6 +190,21 @@ def test_short_file():
         short_file()
 
 
+def test_dxt5_colorblock_alpha_issue_4142():
+    """ Check that colorblocks are decoded correctly in DXT5"""
+
+    with Image.open("Tests/images/dxt5-colorblock-alpha-issue-4142.dds") as im:
+        px = im.getpixel((0, 0))
+        assert px[0] != 0
+        assert px[1] != 0
+        assert px[2] != 0
+
+        px = im.getpixel((1, 0))
+        assert px[0] != 0
+        assert px[1] != 0
+        assert px[2] != 0
+
+
 def test_unimplemented_pixel_format():
     with pytest.raises(NotImplementedError):
         Image.open("Tests/images/unimplemented_pixel_format.dds")