From e87745d9ec34e76fbe236bd3a6ff1225762e04ad Mon Sep 17 00:00:00 2001
From: Christopher Bruns <cmbruns@rotatingpenguin.com>
Date: Mon, 29 Nov 2021 19:38:57 -0800
Subject: [PATCH] Check if installed Qt version supports Format_Grayscale16

---
 Tests/test_imageqt.py | 5 ++++-
 src/PIL/ImageQt.py    | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/Tests/test_imageqt.py b/Tests/test_imageqt.py
index a7947b0a2..08cab9976 100644
--- a/Tests/test_imageqt.py
+++ b/Tests/test_imageqt.py
@@ -42,8 +42,11 @@ def test_rgb():
 
 
 def test_image():
-    for mode in ("1", "RGB", "RGBA", "L", "P", "I;16"):
+    for mode in ("1", "RGB", "RGBA", "L", "P"):
         ImageQt.ImageQt(hopper(mode))
+    qt_format = ImageQt.QImage.Format if ImageQt.qt_version == "6" else ImageQt.QImage
+    if hasattr(qt_format, "Format_Grayscale16"):  # Qt 5.13+
+        ImageQt.ImageQt(hopper("I;16"))
 
 
 def test_closed_file():
diff --git a/src/PIL/ImageQt.py b/src/PIL/ImageQt.py
index f10de3258..8970314d9 100644
--- a/src/PIL/ImageQt.py
+++ b/src/PIL/ImageQt.py
@@ -167,7 +167,7 @@ def _toqclass_helper(im):
     elif im.mode == "RGBA":
         data = im.tobytes("raw", "BGRA")
         format = qt_format.Format_ARGB32
-    elif im.mode == "I;16":
+    elif im.mode == "I;16" and hasattr(qt_format, "Format_Grayscale16"):  # Qt 5.13+
         format = qt_format.Format_Grayscale16
     else:
         if exclusive_fp: