diff --git a/Tests/test_fontfile.py b/Tests/test_fontfile.py
index 206499a047f..575dada86cb 100644
--- a/Tests/test_fontfile.py
+++ b/Tests/test_fontfile.py
@@ -4,7 +4,20 @@
 
 import pytest
 
-from PIL import FontFile
+from PIL import FontFile, Image
+
+
+def test_compile() -> None:
+    font = FontFile.FontFile()
+    font.glyph[0] = ((0, 0), (0, 0, 0, 0), (0, 0, 0, 1), Image.new("L", (0, 0)))
+    font.compile()
+    assert font.ysize == 1
+
+    font.ysize = 2
+    font.compile()
+
+    # Assert that compiling again did not change anything
+    assert font.ysize == 2
 
 
 def test_save(tmp_path: Path) -> None: