diff --git a/gcov.sh b/gcov.sh
index 65f06a4d43b..a9d30b676ff 100755
--- a/gcov.sh
+++ b/gcov.sh
@@ -4,7 +4,7 @@
 # License GPL v2
 
 gcov_init() {
-	USER=`whoami`
+	USER="$(whoami)"
 	firejail --help > /dev/null
 	firemon --help > /dev/null
 	/usr/lib/firejail/fnet --help > /dev/null
@@ -20,7 +20,7 @@ gcov_init() {
 	/usr/lib/firejail/faudit --help > /dev/null
 	/usr/lib/firejail/fbuilder --help > /dev/null
 
-	sudo chown $USER:$USER `find .`
+	find . -exec sudo chown "$USER:$USER" '{}' +
 }
 
 generate() {
@@ -28,7 +28,7 @@ generate() {
 	lcov --add-tracefile gcov-file-old --add-tracefile gcov-file-new  --output-file gcov-file
 	rm -fr gcov-dir
 	genhtml -q gcov-file --output-directory gcov-dir
-	sudo rm `find . -name *.gcda`
+	find . -name '*.gcda' -exec sudo rm '{}' +
 	cp gcov-file gcov-file-old
 	gcov_init
 }
diff --git a/linecnt.sh b/linecnt.sh
index ccce2da82d2..37b4f2a657a 100755
--- a/linecnt.sh
+++ b/linecnt.sh
@@ -4,7 +4,7 @@
 # License GPL v2
 
 gcov_init() {
-	USER=`whoami`
+	USER="$(whoami)"
 	firejail --help > /dev/null
 	firemon --help > /dev/null
 	/usr/lib/firejail/fnet --help > /dev/null
@@ -20,7 +20,7 @@ gcov_init() {
 	/usr/lib/firejail/faudit --help > /dev/null
 	/usr/lib/firejail/fbuilder --help > /dev/null
 
-	sudo chown $USER:$USER `find .`
+	find . -exec sudo chown "$USER:$USER" '{}' +
 }
 
 rm -fr gcov-dir
diff --git a/mkasc.sh b/mkasc.sh
index 31c3f4ffdc5..b41585460c2 100755
--- a/mkasc.sh
+++ b/mkasc.sh
@@ -5,9 +5,9 @@
 
 echo "Calculating SHA256 for all files in /transfer - firejail version $1"
 
-cd /transfer
-sha256sum * > firejail-$1-unsigned
-gpg --clearsign --digest-algo SHA256 < firejail-$1-unsigned > firejail-$1.asc
-gpg --verify firejail-$1.asc
-gpg --detach-sign --armor firejail-$1.tar.xz
-rm firejail-$1-unsigned
+cd /transfer || exit 1
+sha256sum ./* > "firejail-$1-unsigned"
+gpg --clearsign --digest-algo SHA256 < "firejail-$1-unsigned" > "firejail-$1.asc"
+gpg --verify "firejail-$1.asc"
+gpg --detach-sign --armor "firejail-$1.tar.xz"
+rm "firejail-$1-unsigned"
diff --git a/mkdeb.sh.in b/mkdeb.sh.in
index e45acf8eb12..ddd6ca1ee64 100755
--- a/mkdeb.sh.in
+++ b/mkdeb.sh.in
@@ -22,7 +22,7 @@ if [ -n "$HAVE_SELINUX" ]; then
     CONFIG_ARGS="$CONFIG_ARGS --enable-selinux"
 fi
 
-TOP=`pwd`
+TOP="$PWD"
 CODE_ARCHIVE="$NAME-$VERSION.tar.xz"
 CODE_DIR="$NAME-$VERSION"
 INSTALL_DIR="${INSTALL_DIR}${CODE_DIR}/debian"
@@ -35,9 +35,9 @@ echo "install directory: $INSTALL_DIR"
 echo "debian control directory: $DEBIAN_CTRL_DIR"
 echo "*****************************************"
 
-tar -xJvf $CODE_ARCHIVE
-#mkdir -p $INSTALL_DIR
-cd $CODE_DIR
+tar -xJvf "$CODE_ARCHIVE"
+#mkdir -p "$INSTALL_DIR"
+cd "$CODE_DIR"
 ./configure $CONFIG_ARGS
 make -j2
 mkdir debian
@@ -45,26 +45,26 @@ DESTDIR=debian make install-strip
 
 cd ..
 echo "*****************************************"
-SIZE=`du -s $INSTALL_DIR`
+SIZE="$(du -s "$INSTALL_DIR")"
 echo "install size $SIZE"
 echo "*****************************************"
 
-mv $INSTALL_DIR/usr/share/doc/firejail/RELNOTES $INSTALL_DIR/usr/share/doc/firejail/changelog.Debian
-gzip -9 -n $INSTALL_DIR/usr/share/doc/firejail/changelog.Debian
-rm $INSTALL_DIR/usr/share/doc/firejail/COPYING
-install -m644 $CODE_DIR/platform/debian/copyright $INSTALL_DIR/usr/share/doc/firejail/.
-mkdir -p $DEBIAN_CTRL_DIR
-sed "s/FIREJAILVER/$VERSION/g"  $CODE_DIR/platform/debian/control.$(dpkg-architecture -qDEB_HOST_ARCH) > $DEBIAN_CTRL_DIR/control
+mv "$INSTALL_DIR/usr/share/doc/firejail/RELNOTES" "$INSTALL_DIR/usr/share/doc/firejail/changelog.Debian"
+gzip -9 -n "$INSTALL_DIR/usr/share/doc/firejail/changelog.Debian"
+rm "$INSTALL_DIR/usr/share/doc/firejail/COPYING"
+install -m644 "$CODE_DIR/platform/debian/copyright" "$INSTALL_DIR/usr/share/doc/firejail/."
+mkdir -p "$DEBIAN_CTRL_DIR"
+sed "s/FIREJAILVER/$VERSION/g" "$CODE_DIR/platform/debian/control.$(dpkg-architecture -qDEB_HOST_ARCH)" > "$DEBIAN_CTRL_DIR/control"
 
-mkdir -p $INSTALL_DIR/usr/share/lintian/overrides/
-install -m644 $CODE_DIR/platform/debian/firejail.lintian-overrides $INSTALL_DIR/usr/share/lintian/overrides/firejail
+mkdir -p "$INSTALL_DIR/usr/share/lintian/overrides/"
+install -m644 "$CODE_DIR/platform/debian/firejail.lintian-overrides" "$INSTALL_DIR/usr/share/lintian/overrides/firejail"
 
-find $INSTALL_DIR/etc -type f | sed "s,^$INSTALL_DIR,," | LC_ALL=C sort > $DEBIAN_CTRL_DIR/conffiles
-chmod 644 $DEBIAN_CTRL_DIR/conffiles
-find $INSTALL_DIR  -type d | xargs chmod 755
-cd $CODE_DIR
+find "$INSTALL_DIR/etc" -type f | sed "s,^$INSTALL_DIR,," | LC_ALL=C sort > "$DEBIAN_CTRL_DIR/conffiles"
+chmod 644 "$DEBIAN_CTRL_DIR/conffiles"
+find "$INSTALL_DIR" -type d -exec chmod 755 '{}' +
+cd "$CODE_DIR"
 fakeroot dpkg-deb --build debian
 lintian --no-tag-display-limit debian.deb
-mv debian.deb ../firejail_${VERSION}${EXTRA_VERSION}_1_$(dpkg-architecture -qDEB_HOST_ARCH).deb
+mv debian.deb "../firejail_${VERSION}${EXTRA_VERSION}_1_$(dpkg-architecture -qDEB_HOST_ARCH).deb"
 cd ..
-rm -fr $CODE_DIR
+rm -fr "$CODE_DIR"
diff --git a/mkman.sh b/mkman.sh
index 8767972d129..c9606c1e7d0 100755
--- a/mkman.sh
+++ b/mkman.sh
@@ -5,8 +5,8 @@
 
 set -e
 
-sed "s/VERSION/$1/g" $2 > $3
-MONTH=`LC_ALL=C date -u --date="@${SOURCE_DATE_EPOCH:-$(date +%s)}" +%b`
-sed -i "s/MONTH/$MONTH/g" $3
-YEAR=`LC_ALL=C date -u --date="@${SOURCE_DATE_EPOCH:-$(date +%s)}" +%Y`
-sed -i "s/YEAR/$YEAR/g" $3
+sed "s/VERSION/$1/g" "$2" > "$3"
+MONTH="$(LC_ALL=C date -u --date="@${SOURCE_DATE_EPOCH:-$(date +%s)}" +%b)"
+sed -i "s/MONTH/$MONTH/g" "$3"
+YEAR="$(LC_ALL=C date -u --date="@${SOURCE_DATE_EPOCH:-$(date +%s)}" +%Y)"
+sed -i "s/YEAR/$YEAR/g" "$3"
diff --git a/mkuid.sh b/mkuid.sh
index 0264628cc97..47aa42acdc0 100755
--- a/mkuid.sh
+++ b/mkuid.sh
@@ -9,8 +9,8 @@ echo "#define FIREJAIL_UIDS_H" >> uids.h
 
 if [ -r /etc/login.defs ]
 then
-	UID_MIN=`awk '/^\s*UID_MIN\s*([0-9]*).*?$/ {print $2}' /etc/login.defs`
-	GID_MIN=`awk '/^\s*GID_MIN\s*([0-9]*).*?$/ {print $2}' /etc/login.defs`
+	UID_MIN="$(awk '/^\s*UID_MIN\s*([0-9]*).*?$/ {print $2}' /etc/login.defs)"
+	GID_MIN="$(awk '/^\s*GID_MIN\s*([0-9]*).*?$/ {print $2}' /etc/login.defs)"
 fi
 
 # use default values if not found