diff --git a/script/common/confirmation.sh b/script/common/confirmation.sh
index 82dd0ff..67803cf 100644
--- a/script/common/confirmation.sh
+++ b/script/common/confirmation.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -u
 # ******************************************************************************* 
 #                        Confirmation and Passphrase setting 
 # ******************************************************************************* 
diff --git a/script/common/parainstall.sh b/script/common/parainstall.sh
index 8ecca23..6bf48d4 100644
--- a/script/common/parainstall.sh
+++ b/script/common/parainstall.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -u
 # ******************************************************************************* 
 #                        Common part of para-install 
 # ******************************************************************************* 
diff --git a/script/common/parainstall_msg.sh b/script/common/parainstall_msg.sh
index 6d46e32..16f9c1d 100644
--- a/script/common/parainstall_msg.sh
+++ b/script/common/parainstall_msg.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -u
 
 function parainstall_msg() {
 
diff --git a/script/common/preinstall.sh b/script/common/preinstall.sh
index 4d555bc..6d51982 100644
--- a/script/common/preinstall.sh
+++ b/script/common/preinstall.sh
@@ -1,3 +1,4 @@
+#!/bin/bash -u
 # ******************************************************************************* 
 #                                Pre-install stage 
 # ******************************************************************************* 
diff --git a/script/ubuntu-kaiten-yaki.sh b/script/ubuntu-kaiten-yaki.sh
index 3bf32f7..54d4192 100644
--- a/script/ubuntu-kaiten-yaki.sh
+++ b/script/ubuntu-kaiten-yaki.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -u
 
 # Load configuration parameter
 source config.sh
@@ -71,9 +71,7 @@ fi
 # ******************************************************************************* 
 
 # Show common message to let the operator focus on the critical part
-if ! parainstall ; then
-	return 1
-fi
+parainstall_msg
 
 # Ubuntu dependent message
 cat <<HEREDOC
@@ -98,7 +96,9 @@ installer_pid=$!
 # Common part of the para-install. 
 # Record the install PID, modify the /etc/default/grub of the target, 
 # and then, wait for the end of sintaller. 
-parainstall_msg
+if ! parainstall ; then
+	return 1
+fi
 
 # ******************************************************************************* 
 #                                Post-install stage 
diff --git a/script/void-kaiten-yaki.sh b/script/void-kaiten-yaki.sh
index b3d172f..f7eac31 100644
--- a/script/void-kaiten-yaki.sh
+++ b/script/void-kaiten-yaki.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/bash -u
 
 # Load configuration parameter
 source config.sh
@@ -85,10 +85,7 @@ sed -i "s#loglevel=4#loglevel=4 rd.auto=1 cryptdevice=/dev/sda2:${LUKS_NAME} roo
 # ******************************************************************************* 
 
 # Show common message to let the operator focus on the critical part
-if ! parainstall ; then
-	return 1
-fi
-
+parainstall_msg
 # Ubuntu dependent message
 cat <<HEREDOC
 
@@ -116,7 +113,9 @@ installer_pid=$!
 # Common part of the para-install. 
 # Record the install PID, modify the /etc/default/grub of the target, 
 # and then, wait for the end of sintaller. 
-source common/_parainstall.sh
+if ! parainstall ; then
+	return 1
+fi
 
 # ******************************************************************************* 
 #                                Post-install stage