diff --git a/setup.cfg b/setup.cfg
index 1822e73..6b1856e 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -23,6 +23,7 @@ install_requires =
 [options.extras_require]
 test =
     pytest-astropy
+    pytest-openfiles
     pytest-cov
     scikit-image
 docs =