diff --git a/pyproject.toml b/pyproject.toml
index 94b9839b..15476926 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -23,7 +23,7 @@ requires-python = ">=3.7"
 dynamic = ["version"]
 dependencies = [
     "dnaio >= 0.10.0",
-    "xopen >= 1.6.0",
+    "xopen == 1.7",
 ]
 
 [project.urls]