--- scripts/plymouth-set-default-theme.ina	2012-07-15 12:16:53.083156390 +0300
+++ scripts/plymouth-set-default-theme.in	2012-07-15 12:17:32.715893173 +0300
@@ -173,7 +173,10 @@
         exit $?
 fi
 
-if [ ! -e ${PLYMOUTH_DATADIR}/plymouth/themes/${THEME_NAME}/${THEME_NAME}.plymouth ]; then
+if [ -z ${THEME_NAME} ]; then
+        echo "Please specify a theme name"
+        exit 1
+elif [ ! -e ${PLYMOUTH_DATADIR}/plymouth/themes/${THEME_NAME}/${THEME_NAME}.plymouth ]; then
         echo "${PLYMOUTH_DATADIR}/plymouth/themes/${THEME_NAME}/${THEME_NAME}.plymouth does not exist" > /dev/stderr
         exit 1
 fi