diff --git a/Tests/images/black_and_white.ico b/Tests/images/black_and_white.ico
new file mode 100644
index 000000000..f98d7ac8e
Binary files /dev/null and b/Tests/images/black_and_white.ico differ
diff --git a/Tests/test_file_ico.py b/Tests/test_file_ico.py
index 1a5a695fa..7b9e4e698 100644
--- a/Tests/test_file_ico.py
+++ b/Tests/test_file_ico.py
@@ -18,6 +18,12 @@ def test_sanity():
     assert im.get_format_mimetype() == "image/x-icon"
 
 
+def test_black_and_white():
+    with Image.open("Tests/images/black_and_white.ico") as im:
+        assert im.mode == "RGBA"
+        assert im.size == (16, 16)
+
+
 def test_invalid_file():
     with open("Tests/images/flower.jpg", "rb") as fp:
         with pytest.raises(SyntaxError):
diff --git a/src/PIL/IcoImagePlugin.py b/src/PIL/IcoImagePlugin.py
index ff92390fb..dbc108d7b 100644
--- a/src/PIL/IcoImagePlugin.py
+++ b/src/PIL/IcoImagePlugin.py
@@ -190,13 +190,7 @@ class IcoFile:
             im.tile[0] = d, (0, 0) + im.size, o, a
 
             # figure out where AND mask image starts
-            mode = a[0]
-            bpp = 8
-            for k, v in BmpImagePlugin.BIT2MODE.items():
-                if mode == v[1]:
-                    bpp = k
-                    break
-
+            bpp = header["bpp"]
             if 32 == bpp:
                 # 32-bit color depth icon image allows semitransparent areas
                 # PIL's DIB format ignores transparency bits, recover them.