diff --git a/webshell/tests/viewer/mozilla-viewer.sh b/webshell/tests/viewer/mozilla-viewer.sh
index 7911d8fed8dd..d06d4cd24eaf 100755
--- a/webshell/tests/viewer/mozilla-viewer.sh
+++ b/webshell/tests/viewer/mozilla-viewer.sh
@@ -33,35 +33,41 @@ dist_bin=""
 # Running from dist/bin
 if [ -d components -a -d res ]
 then
-	dist_bin="./"
+  dist_bin="./"
 else
-	# Running from source dir
-	if [ -f Makefile.in ]
-	then
-		dist_bin=`grep -w DEPTH Makefile.in  | grep -e "\.\." | awk -F"=" '{ print $2; }'`/dist/bin
-	fi
+  # Running from source dir
+  if [ -f Makefile.in ]
+  then
+    depth=`perl -ne '/^DEPTH\s*=(.*)/ and print $1' Makefile.in`
+    dist_bin=$depth/dist/bin
+  fi
 fi
 
 script_args=""
 
-while [ -n "$(echo $1 | grep '^-')" ]
+while [ $# -gt 0 ]
 do
-	case $1 in
-		-h | --help)
-			script_args="$script_args -h"
-			;;
-
-		-g | --debug)
-			script_args="$script_args -g"
-			;;
-
-		-d | --debugger)
-			script_args="$script_args -d $2"
-
-			shift
-			;;
-	esac
-	shift
+  case $1 in
+    -h | --help)
+      script_args="$script_args -h"
+      shift
+      ;;
+    -g | --debug)
+      script_args="$script_args -g"
+      shift
+      ;;
+    -d | --debugger)
+      script_args="$script_args -d $2"
+      shift 2
+      ;;
+    -*)
+      echo "Unknown option: $1" 1>&2
+      exit 1
+      ;;
+    *)
+      break
+      ;;
+ esac
 done
 
 $dist_bin/run-mozilla.sh $script_args ./viewer ${1+"$@"}