diff --git a/debian/mariadb-common.postinst b/debian/mariadb-common.postinst
index 53d131a3929..0292a88c6f9 100644
--- a/debian/mariadb-common.postinst
+++ b/debian/mariadb-common.postinst
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 set -e
 
diff --git a/debian/mariadb-common.postrm b/debian/mariadb-common.postrm
index 2548733a1b9..d807c63aec9 100644
--- a/debian/mariadb-common.postrm
+++ b/debian/mariadb-common.postrm
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 set -e
 
diff --git a/debian/mariadb-plugin-mroonga.postinst b/debian/mariadb-plugin-mroonga.postinst
index fea327c204d..7c6da36391b 100644
--- a/debian/mariadb-plugin-mroonga.postinst
+++ b/debian/mariadb-plugin-mroonga.postinst
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 set -e
 
diff --git a/debian/mariadb-plugin-mroonga.prerm b/debian/mariadb-plugin-mroonga.prerm
index 54cba1e74ff..0fde33765e8 100644
--- a/debian/mariadb-plugin-mroonga.prerm
+++ b/debian/mariadb-plugin-mroonga.prerm
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 
 set -e
 
diff --git a/debian/mariadb-server.preinst b/debian/mariadb-server.preinst
index eb0b825ca28..418273bbb27 100644
--- a/debian/mariadb-server.preinst
+++ b/debian/mariadb-server.preinst
@@ -1,4 +1,4 @@
-#!/bin/bash -e
+#!/bin/bash
 #
 # summary of how this script can be called:
 #        * <new-preinst> install
@@ -7,6 +7,8 @@
 #        * <old-preinst> abort-upgrade <new-version>
 #
 
+set -e
+
 # shellcheck source=/dev/null
 . /usr/share/debconf/confmodule
 
diff --git a/debian/mariadb-server.prerm b/debian/mariadb-server.prerm
index 2701fa5fc36..e46f1d7817a 100644
--- a/debian/mariadb-server.prerm
+++ b/debian/mariadb-server.prerm
@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/bin/bash
 set -e
 
 #DEBHELPER#