diff --git a/pyproject.toml b/pyproject.toml
index 34b08da6..ed8018aa 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -64,7 +64,7 @@ opentype = [
     "fonttools>=4.33.3",
     # uharfbuzz sometimes includes breaking changes, so
     # we set an explicit range
-    "uharfbuzz>=0.25.0,<0.39.0",
+    "uharfbuzz>=0.25.0,<0.40.0",
 ]
 image-support = [
     # Only tested systematically on 8.x,