diff --git a/Tests/images/unknown_compression_method.png b/Tests/images/unknown_compression_method.png
new file mode 100644
index 000000000..e1614a731
Binary files /dev/null and b/Tests/images/unknown_compression_method.png differ
diff --git a/Tests/test_file_png.py b/Tests/test_file_png.py
index 1a8d58bd6..30fb14c44 100644
--- a/Tests/test_file_png.py
+++ b/Tests/test_file_png.py
@@ -619,6 +619,10 @@ class TestFilePng:
         with Image.open("Tests/images/hopper_idat_after_image_end.png") as im:
             assert im.text == {"TXT": "VALUE", "ZIP": "VALUE"}
 
+    def test_unknown_compression_method(self) -> None:
+        with pytest.raises(SyntaxError, match="Unknown compression method"):
+            PngImagePlugin.PngImageFile("Tests/images/unknown_compression_method.png")
+
     def test_padded_idat(self) -> None:
         # This image has been manually hexedited
         # so that the IDAT chunk has padding at the end
diff --git a/src/PIL/PngImagePlugin.py b/src/PIL/PngImagePlugin.py
index 1e5a1a464..d922bacfb 100644
--- a/src/PIL/PngImagePlugin.py
+++ b/src/PIL/PngImagePlugin.py
@@ -392,8 +392,8 @@ class PngStream(ChunkStream):
         # Compressed profile    n bytes (zlib with deflate compression)
         i = s.find(b"\0")
         logger.debug("iCCP profile name %r", s[:i])
-        logger.debug("Compression method %s", s[i])
-        comp_method = s[i]
+        comp_method = s[i + 1]
+        logger.debug("Compression method %s", comp_method)
         if comp_method != 0:
             msg = f"Unknown compression method {comp_method} in iCCP chunk"
             raise SyntaxError(msg)