diff --git a/plugins/oracle/oracle_sysstat_ b/plugins/oracle/oracle_sysstat_
index 4cabf842..d2a2afc7 100755
--- a/plugins/oracle/oracle_sysstat_
+++ b/plugins/oracle/oracle_sysstat_
@@ -78,21 +78,21 @@
 #%# capabilities=autoconf suggest
 
 # Include plugin.sh
-. $MUNIN_LIBDIR/plugins/plugin.sh
+. "${MUNIN_LIBDIR}/plugins/plugin.sh"
 
 # Like perl 'use strict;' 
 #set -o nounset
 
 # Environments
-: ${ORACLE_HOME:=$( echo /opt/oracle/product/* )}
-: ${ORACLE_SID:=orcl}
-: ${oracle_auth:=/ as SYSDBA}
+: "${ORACLE_HOME:=$( echo /opt/oracle/product/* )}"
+: "${ORACLE_SID:=orcl}"
+: "${oracle_auth:=/ as SYSDBA}"
 
 PATH=$PATH:$ORACLE_HOME/bin
 export PATH ORACLE_HOME ORACLE_SID
 
 # Module name
-module=$( basename $0 | sed -e 's/^.*_//' )
+module=$( basename "$0" | sed -e 's/^.*_//' )
 
 # Graph settings
 declare -A global_attrs  # required
@@ -476,7 +476,7 @@ sqlplus_variables="
 # functions 
 
 autoconf() {
-    if [ -x "$( which ${sqlplus} )" ]; then
+    if [ -x "$( which "${sqlplus}" )" ]; then
         echo yes
     else
         echo "no (failed to find executable 'sqlplus')"
@@ -484,7 +484,7 @@ autoconf() {
 }
 
 suggest() {
-    echo ${!global_attrs[@]} | tr ' ' '\n' | sort
+    echo "${!global_attrs[@]}" | tr ' ' '\n' | sort
 }
 
 config() {
@@ -503,12 +503,12 @@ config() {
         draw="${t[2]}"
         label="${t[3]}"
 
-        echo ${field}.type  ${type}
-        echo ${field}.draw  ${draw}
-        echo ${field}.label ${label}
+        echo "${field}.type"  "$type"
+        echo "${field}.draw"  "$draw"
+        echo "${field}.label" "$label"
     done <<< "${data_attrs[$module]}"
 
-    echo graph_order ${fields[@]}
+    echo graph_order "${fields[@]}"
 }
 
 getfield() {