diff --git a/contrib/check-config.sh b/contrib/check-config.sh
index fcbd874ff2..5cedbd541c 100755
--- a/contrib/check-config.sh
+++ b/contrib/check-config.sh
@@ -16,7 +16,7 @@ possibleConfigs=(
 if [ $# -gt 0 ]; then
 	CONFIG="$1"
 else
-	: ${CONFIG:="${possibleConfigs[0]}"}
+	: "${CONFIG:="${possibleConfigs[0]}"}"
 fi
 
 if ! command -v zgrep &> /dev/null; then
@@ -156,13 +156,13 @@ echo 'Generally Necessary:'
 echo -n '- '
 cgroupSubsystemDir="$(awk '/[, ](cpu|cpuacct|cpuset|devices|freezer|memory)[, ]/ && $3 == "cgroup" { print $2 }' /proc/mounts | head -n1)"
 cgroupDir="$(dirname "$cgroupSubsystemDir")"
-if [ -d "$cgroupDir/cpu" -o -d "$cgroupDir/cpuacct" -o -d "$cgroupDir/cpuset" -o -d "$cgroupDir/devices" -o -d "$cgroupDir/freezer" -o -d "$cgroupDir/memory" ]; then
+if [ -d "$cgroupDir/cpu" ] || [ -d "$cgroupDir/cpuacct" ] || [ -d "$cgroupDir/cpuset" ] || [  -d "$cgroupDir/devices" ] || [ -d "$cgroupDir/freezer" ] || [ -d "$cgroupDir/memory" ]; then
 	echo "$(wrap_good 'cgroup hierarchy' 'properly mounted') [$cgroupDir]"
 else
 	if [ "$cgroupSubsystemDir" ]; then
 		echo "$(wrap_bad 'cgroup hierarchy' 'single mountpoint!') [$cgroupSubsystemDir]"
 	else
-		echo "$(wrap_bad 'cgroup hierarchy' 'nonexistent??')"
+		wrap_bad 'cgroup hierarchy' 'nonexistent??'
 	fi
 	EXITCODE=1
 	echo "    $(wrap_color '(see https://github.com/tianon/cgroupfs-mount)' yellow)"
@@ -171,16 +171,16 @@ fi
 if [ "$(cat /sys/module/apparmor/parameters/enabled 2>/dev/null)" = 'Y' ]; then
 	echo -n '- '
 	if command -v apparmor_parser &> /dev/null; then
-		echo "$(wrap_good 'apparmor' 'enabled and tools installed')"
+		wrap_good 'apparmor' 'enabled and tools installed'
 	else
-		echo "$(wrap_bad 'apparmor' 'enabled, but apparmor_parser missing')"
+		wrap_bad 'apparmor' 'enabled, but apparmor_parser missing'
 		echo -n '    '
 		if command -v apt-get &> /dev/null; then
-			echo "$(wrap_color '(use "apt-get install apparmor" to fix this)')"
+			wrap_color '(use "apt-get install apparmor" to fix this)'
 		elif command -v yum &> /dev/null; then
-			echo "$(wrap_color '(your best bet is "yum install apparmor-parser")')"
+			wrap_color '(your best bet is "yum install apparmor-parser")'
 		else
-			echo "$(wrap_color '(look for an "apparmor" package for your distribution)')"
+			wrap_color '(look for an "apparmor" package for your distribution)'
 		fi
 		EXITCODE=1
 	fi
@@ -199,7 +199,7 @@ flags=(
 	POSIX_MQUEUE
 )
 check_flags "${flags[@]}"
-if [ "$kernelMajor" -lt 4 ] || [ "$kernelMajor" -eq 4 -a "$kernelMinor" -lt 8 ]; then
+if [ "$kernelMajor" -lt 4 ] || ( [ "$kernelMajor" -eq 4 ] && [ "$kernelMinor" -lt 8 ] ); then
         check_flags DEVPTS_MULTIPLE_INSTANCES
 fi
 
@@ -245,15 +245,15 @@ echo 'Optional Features:'
 	fi
 }
 
-if [ "$kernelMajor" -lt 4 ] || [ "$kernelMajor" -eq 4 -a "$kernelMinor" -le 5 ]; then
+if [ "$kernelMajor" -lt 4 ] || ( [ "$kernelMajor" -eq 4 ] && [ "$kernelMinor" -le 5 ] ); then
 	check_flags MEMCG_KMEM
 fi
 
-if [ "$kernelMajor" -lt 3 ] || [ "$kernelMajor" -eq 3 -a "$kernelMinor" -le 18 ]; then
+if [ "$kernelMajor" -lt 3 ] || ( [ "$kernelMajor" -eq 3 ] && [ "$kernelMinor" -le 18 ] ); then
 	check_flags RESOURCE_COUNTERS
 fi
 
-if [ "$kernelMajor" -lt 3 ] || [ "$kernelMajor" -eq 3 -a "$kernelMinor" -le 13 ]; then
+if [ "$kernelMajor" -lt 3 ] || ( [ "$kernelMajor" -eq 3 ] && [ "$kernelMinor" -le 13 ] ); then
 	netprio=NETPRIO_CGROUP
 else
 	netprio=CGROUP_NET_PRIO
@@ -291,16 +291,16 @@ if ! is_set EXT4_FS || ! is_set EXT4_FS_POSIX_ACL || ! is_set EXT4_FS_SECURITY;
 fi
 
 echo '- Network Drivers:'
-echo '  - "'$(wrap_color 'overlay' blue)'":'
+echo "  - \"$(wrap_color 'overlay' blue)\":"
 check_flags VXLAN | sed 's/^/    /'
 echo '      Optional (for encrypted networks):'
 check_flags CRYPTO CRYPTO_AEAD CRYPTO_GCM CRYPTO_SEQIV CRYPTO_GHASH \
             XFRM XFRM_USER XFRM_ALGO INET_ESP INET_XFRM_MODE_TRANSPORT | sed 's/^/      /'
-echo '  - "'$(wrap_color 'ipvlan' blue)'":'
+echo "  - \"$(wrap_color 'ipvlan' blue)\":"
 check_flags IPVLAN | sed 's/^/    /'
-echo '  - "'$(wrap_color 'macvlan' blue)'":'
+echo "  - \"$(wrap_color 'macvlan' blue)\":"
 check_flags MACVLAN DUMMY | sed 's/^/    /'
-echo '  - "'$(wrap_color 'ftp,tftp client in container' blue)'":'
+echo "  - \"$(wrap_color 'ftp,tftp client in container' blue)\":"
 check_flags NF_NAT_FTP NF_CONNTRACK_FTP NF_NAT_TFTP NF_CONNTRACK_TFTP | sed 's/^/    /'
 
 # only fail if no storage drivers available
@@ -309,7 +309,7 @@ EXITCODE=0
 STORAGE=1
 
 echo '- Storage Drivers:'
-echo '  - "'$(wrap_color 'aufs' blue)'":'
+echo "  - \"$(wrap_color 'aufs' blue)\":"
 check_flags AUFS_FS | sed 's/^/    /'
 if ! is_set AUFS_FS && grep -q aufs /proc/filesystems; then
 	echo "      $(wrap_color '(note that some kernels include AUFS patches but not the AUFS_FS flag)' bold black)"
@@ -317,23 +317,23 @@ fi
 [ "$EXITCODE" = 0 ] && STORAGE=0
 EXITCODE=0
 
-echo '  - "'$(wrap_color 'btrfs' blue)'":'
+echo "  - \"$(wrap_color 'btrfs' blue)\":"
 check_flags BTRFS_FS | sed 's/^/    /'
 check_flags BTRFS_FS_POSIX_ACL | sed 's/^/    /'
 [ "$EXITCODE" = 0 ] && STORAGE=0
 EXITCODE=0
 
-echo '  - "'$(wrap_color 'devicemapper' blue)'":'
+echo "  - \"$(wrap_color 'devicemapper' blue)\":"
 check_flags BLK_DEV_DM DM_THIN_PROVISIONING | sed 's/^/    /'
 [ "$EXITCODE" = 0 ] && STORAGE=0
 EXITCODE=0
 
-echo '  - "'$(wrap_color 'overlay' blue)'":'
+echo "  - \"$(wrap_color 'overlay' blue)\":"
 check_flags OVERLAY_FS | sed 's/^/    /'
 [ "$EXITCODE" = 0 ] && STORAGE=0
 EXITCODE=0
 
-echo '  - "'$(wrap_color 'zfs' blue)'":'
+echo "  - \"$(wrap_color 'zfs' blue)\":"
 echo -n "    - "; check_device /dev/zfs
 echo -n "    - "; check_command zfs
 echo -n "    - "; check_command zpool
@@ -347,12 +347,12 @@ echo
 
 check_limit_over()
 {
-	if [ $(cat "$1") -le "$2" ]; then
-		wrap_bad "- $1" "$(cat $1)"
+	if [ "$(cat "$1")" -le "$2" ]; then
+		wrap_bad "- $1" "$(cat "$1")"
 		wrap_color "    This should be set to at least $2, for example set: sysctl -w kernel/keys/root_maxkeys=1000000" bold black
 		EXITCODE=1
 	else
-		wrap_good "- $1" "$(cat $1)"
+		wrap_good "- $1" "$(cat "$1")"
 	fi
 }