diff --git a/Tests/images/hopper.imt b/Tests/images/hopper.imt
new file mode 100644
index 00000000000..d765cf95fac
Binary files /dev/null and b/Tests/images/hopper.imt differ
diff --git a/Tests/test_file_imt.py b/Tests/test_file_imt.py
new file mode 100644
index 00000000000..3bcc97b077a
--- /dev/null
+++ b/Tests/test_file_imt.py
@@ -0,0 +1,19 @@
+import io
+
+import pytest
+
+from PIL import Image, ImtImagePlugin
+
+from .helper import assert_image_equal_tofile
+
+
+def test_sanity():
+    with Image.open("Tests/images/hopper.imt") as im:
+        assert_image_equal_tofile(im, "Tests/images/bw_gradient.png")
+
+
+@pytest.mark.parametrize("data", (b"\n", b"\n-", b"width 1\n"))
+def test_invalid_file(data):
+    with io.BytesIO(data) as fp:
+        with pytest.raises(SyntaxError):
+            ImtImagePlugin.ImtImageFile(fp)
diff --git a/src/PIL/ImtImagePlugin.py b/src/PIL/ImtImagePlugin.py
index 5790acdaf52..5bcb959f143 100644
--- a/src/PIL/ImtImagePlugin.py
+++ b/src/PIL/ImtImagePlugin.py
@@ -74,13 +74,13 @@ def _open(self):
                 if not m:
                     break
                 k, v = m.group(1, 2)
-                if k == "width":
+                if k == b"width":
                     xsize = int(v)
                     self._size = xsize, ysize
-                elif k == "height":
+                elif k == b"height":
                     ysize = int(v)
                     self._size = xsize, ysize
-                elif k == "pixel" and v == "n8":
+                elif k == b"pixel" and v == b"n8":
                     self.mode = "L"