diff --git a/tox.cover.sh b/tox.cover.sh
index 80b6474d7..9a2c3f141 100755
--- a/tox.cover.sh
+++ b/tox.cover.sh
@@ -15,6 +15,8 @@ cover () {
             "$1" --cover-min-percentage="$2" "$1"
 }
 
+rm -f .coverage  # --cover-erase is off, make sure stats are correct
+
 # don't use sequential composition (;), if letsencrypt_nginx returns
 # 0, coveralls submit will be triggered (c.f. .travis.yml,
 # after_success)