diff --git a/lib/self-upgrade.bash b/lib/self-upgrade.bash
index ae7b97d..267e01f 100644
--- a/lib/self-upgrade.bash
+++ b/lib/self-upgrade.bash
@@ -9,7 +9,7 @@
 
 function self_upgrade {
   mv "$MIAOU_BASH_DIR" "$MIAOU_BASH_DIR".before_upgrade
-  "$MIAOU_BASH_DIR".before_upgrade/install.sh upgraded
+  bash "$MIAOU_BASH_DIR".before_upgrade/install.sh upgraded
   rm -rf "$MIAOU_BASH_DIR".before_upgrade
   echo -n "version: "
   . "$MIAOU_BASH_DIR"/bin/miaou-bash --version