diff --git a/build.sh b/build.sh
index 0ab247e..a68d0c7 100755
--- a/build.sh
+++ b/build.sh
@@ -1,47 +1,48 @@
-# !/bin/bash
+# !/bin/sh
 # set -x
 
-OUTFLDR=dist
-if [ -d ${OUTFLDR} ]
-then
-	rm -f ${OUTFLDR}/*
-else
-	mkdir ${OUTFLDR}
-fi
-
-GCCOPT="--charset UTF-8 --compilation_level SIMPLE_OPTIMIZATIONS --warning_level VERBOSE"
-GCCEXT="--externs closure/google-ext.js --externs closure/forge-ext.js --externs closure/pdflib-ext.js --externs closure/zb-externs.js"
-jss=""
-while read js
-do
-	if [ -n "${js}" ]
+echo "
+zgacertsutil.js
+zgapdfcryptor.js
+zgapdfsigner.js
+zgaindex.js
+" | {
+	OUTFLDR=dist
+	if [ -d ${OUTFLDR} ]
 	then
-		c=$(echo "${js}" | cut -b1)
-		if [ "$c" != "#" ]
+		rm -f ${OUTFLDR}/*
+	else
+		mkdir ${OUTFLDR}
+	fi
+	GCCOPT="--charset UTF-8 --compilation_level SIMPLE_OPTIMIZATIONS --warning_level VERBOSE"
+	GCCEXT="--externs closure/google-ext.js --externs closure/forge-ext.js --externs closure/pdflib-ext.js --externs closure/zb-externs.js"
+	jss=""
+	while read js
+	do
+		if [ -n "${js}" ]
 		then
-			outf="${OUTFLDR}/_${js}"
-			sed -e "s/\/\/Only for nodejs Start\/\//\/*/g" -e "s/\/\/Only for nodejs End\/\//*\//g" "lib/${js}" > "${outf}"
-			if [ $? -eq 0 ]
+			c=$(echo "${js}" | cut -b1)
+			if [ "$c" != "#" ]
 			then
-				echo "Created js file: ${outf}"
-				jss="${jss} --js ${outf}"
-			else
-				echo "Failed create js file: ${outf}"
-				exit 10
+				outf="${OUTFLDR}/_${js}"
+				sed -e "s/\/\/Only for nodejs Start\/\//\/*/g" -e "s/\/\/Only for nodejs End\/\//*\//g" "lib/${js}" > "${outf}"
+				if [ $? -eq 0 ]
+				then
+					echo "Created js file: ${outf}"
+					jss="${jss} --js ${outf}"
+				else
+					echo "Failed create js file: ${outf}"
+					exit 10
+				fi
 			fi
 		fi
+	done
+	npx google-closure-compiler ${GCCOPT} ${GCCEXT} ${jss} --js_output_file ${OUTFLDR}/zgapdfsigner.min.js
+	if [ $? -ne 0 ]
+	then
+		echo "google-closure-compiler failed."
+		exit 20
 	fi
-done <<< "
-zgacertsutil.js
-zgapdfcryptor.js
-zgapdfsigner.js
-zgaindex.js
-"
-npx google-closure-compiler ${GCCOPT} ${GCCEXT} ${jss} --js_output_file ${OUTFLDR}/zgapdfsigner.min.js
-if [ $? -ne 0 ]
-then
-	echo "google-closure-compiler failed."
-	exit 20
-fi
-
-exit 0
+	exit 0
+}
+exit $?