diff --git a/init.d/sysv/zapret b/init.d/sysv/zapret
index 7ee044b..f8bf3ba 100755
--- a/init.d/sysv/zapret
+++ b/init.d/sysv/zapret
@@ -118,7 +118,7 @@ run_daemon()
 		PID=$(jobs -p %$JOBCT)
 		if [ -n "$PID" ]; then
 			echo $PID >$PIDFILE
-			JOBCT=`expr $JOBCT + 1`
+			JOBCT=$(($JOBCT+1))
 		else
 			echo could not start daemon $1 : $2 $3
 		fi
diff --git a/install_easy.sh b/install_easy.sh
index 0de1234..a0441cc 100755
--- a/install_easy.sh
+++ b/install_easy.sh
@@ -103,7 +103,7 @@ ask_list()
 	n=1
 	for m in $2; do
 		echo $n : $m
-		n=`expr $n + 1`
+		n=$(($n+1))
 	done
 	echo -n "your choice (default : $M_DEFAULT) : "
 	read m
@@ -424,7 +424,7 @@ openwrt_fw_section_find()
 		 	true
 	 		return
 		}
-		i=`expr $i + 1`
+		i=$(($i+1))
 	done
 	false
 	return
diff --git a/uninstall_easy.sh b/uninstall_easy.sh
index d044751..2f5dfbe 100755
--- a/uninstall_easy.sh
+++ b/uninstall_easy.sh
@@ -135,7 +135,7 @@ openwrt_fw_section_find()
 		 	true
 	 		return
 		}
-		i=`expr $i + 1`
+		i=$(($i+1))
 	done
 	false
 	return