diff --git a/script/test-module b/script/test-module
index df61a7d..8148d73 100755
--- a/script/test-module
+++ b/script/test-module
@@ -31,7 +31,7 @@ elif [ -f pyproject.toml ]; then
   # install poetry
   pip install poetry
   # make sure that poetry doesn't blow away our locally installed octodns
-  sed -i '' '/^octodns =/d' pyproject.toml
+  sed -i'.bak' '/^octodns =/d' pyproject.toml
   # now install all the deps
   poetry install --no-root -v
 else