diff --git a/jenkins.sh b/jenkins.sh
index fa99e557d6..a2f28ffb8f 100644
--- a/jenkins.sh
+++ b/jenkins.sh
@@ -14,5 +14,8 @@ npm install ./node_modules/matrix-js-sdk-*.tgz
 # install the other dependencies
 npm install
 
+# delete the old tarball, if it exists
+rm -f matrix-react-sdk-*.tgz
+
 # build our tarball
 npm pack