diff --git a/release/merge.sh b/release/merge.sh
index f53563a4..77eb0802 100755
--- a/release/merge.sh
+++ b/release/merge.sh
@@ -67,7 +67,7 @@ git push --tags upstream master
 
 git checkout develop
 dev_version="$version.dev0"
-sed --in-place= -e s/$(python smart_open/version.py)/$dev_version/ smart_open/version.py
+sed --in-place="" -e s/$(python smart_open/version.py)/$dev_version/ smart_open/version.py
 git commit smart_open/version.py -m "bump version to $dev_version"
 git push upstream develop
 
diff --git a/release/prepare.sh b/release/prepare.sh
index 2405a438..ab86505e 100755
--- a/release/prepare.sh
+++ b/release/prepare.sh
@@ -33,7 +33,7 @@ git branch -D release-"$version"
 set -e
 
 git checkout upstream/develop -b release-"$version"
-sed -i "" -e "s/$(python smart_open/version.py)/$version/" smart_open/version.py
+sed --in-place="" -e "s/$(python smart_open/version.py)/$version/" smart_open/version.py
 git commit smart_open/version.py -m "bump version to $version"
 
 echo "Next, update CHANGELOG.md."