diff --git a/tox.ini b/tox.ini
index fe66108df..2999f2371 100644
--- a/tox.ini
+++ b/tox.ini
@@ -129,7 +129,7 @@ commands_pre =
 commands=
     pytest astropy/astropy/io/misc/asdf --open-files --run-slow --remote-data \
         -W "ignore::asdf.exceptions.AsdfDeprecationWarning:asdf.types" \
-        -W "ignore::asdf.exceptions.AsdfDeprecationWarning:asdf.extension" \
+        -W "ignore::asdf.exceptions.AsdfDeprecationWarning:asdf.extension"
 
 [testenv:asdf-astropy]
 change_dir = {env_tmp_dir}