diff --git a/mender-convert-modify b/mender-convert-modify
index ae0efc7..dc67d29 100755
--- a/mender-convert-modify
+++ b/mender-convert-modify
@@ -105,7 +105,7 @@ if [ "${MENDER_CLIENT_INSTALL}" = "y" ]; then
     deb_get_and_install_pacakge mender-client "${MENDER_CLIENT_VERSION}"
 
     # Save installed client version for tests in Yocto variable format
-    testscfg_add "PREFERRED_VERSION_mender-client" "$(echo ${DEB_NAME} | sed -r 's/.*_([0-9]+\.[0-9]+\.[0-9]+).*/\1/')"
+    testscfg_add "PREFERRED_VERSION:mender-client" "$(echo ${DEB_NAME} | sed -r 's/.*_([0-9]+\.[0-9]+\.[0-9]+).*/\1/')"
 fi
 
 if [ "${MENDER_ENABLE_SYSTEMD}" == "y" ]; then