--- a/build-aux/testrunner.sh
+++ b/build-aux/testrunner.sh
@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/bin/sh
 # testrunner.sh
 #
 # Copyright (C) 2006-2008  Jürg Billeter
@@ -26,14 +26,22 @@
 
 EXTRA_ENVIRONMENT_FILE=tests-extra-environment.sh
 
+sanitize_name() {
+	printf '%s\n' "$1" | tr '/-' '__'
+}
+
+package_flags() {
+	for package in $PACKAGES; do
+		printf ' --pkg %s' "$package"
+	done
+}
+
 testfile=$1
-testdirname="$(dirname $testfile)"
+testdirname=$(dirname "$testfile")
 testfile=${testfile#$srcdir/}
-testpath=${testfile/.*/}
-testpath=${testpath//\//_}
-testpath=${testpath//-/_}
-if test -f $testdirname/$EXTRA_ENVIRONMENT_FILE; then
-	source $testdirname/$EXTRA_ENVIRONMENT_FILE
+testpath=$(sanitize_name "${testfile%.*}")
+if test -f "$testdirname/$EXTRA_ENVIRONMENT_FILE"; then
+	. "$testdirname/$EXTRA_ENVIRONMENT_FILE"
 fi
 
 vapidir=$abs_top_srcdir/vapi
@@ -57,21 +65,25 @@
 
 # Incorporate the TEST_CFLAGS.
 for cflag in ${TEST_CFLAGS}; do
-    VALAFLAGS="${VALAFLAGS} -X ${cflag}"
+	VALAFLAGS="${VALAFLAGS} -X ${cflag}"
 done
 
 # Incorporate the user's CFLAGS. Matters if the user decided to insert
 # -m32 in CFLAGS, for example.
 for cflag in ${CFLAGS} ${CPPFLAGS} ${LDFLAGS}; do
-	if [[ ! $cflag =~ ^\-O[0-9]$ ]]; then
-		VALAFLAGS="${VALAFLAGS} -X ${cflag}"
-	fi
+	case $cflag in
+		-O[0-9])
+			;;
+		*)
+			VALAFLAGS="${VALAFLAGS} -X ${cflag}"
+			;;
+	esac
 done
 
-function testheader() {
+testheader() {
 	if [ "$1" = "Packages:" ]; then
 		shift
-		PACKAGES="$PACKAGES $@"
+		PACKAGES="$PACKAGES $*"
 	elif [ "$*" = "Invalid Code" ]; then
 		INVALIDCODE=1
 		INHEADER=0
@@ -84,21 +96,19 @@
 	fi
 }
 
-function sourceheader() {
+sourceheader() {
 	if [ "$1" = "Program:" ]; then
 		if [ "$2" = "server" ]; then
 			ISSERVER=1
 		fi
-		ns=$testpath/$2
-		ns=${ns//\//_}
-		ns=${ns//-/_}
+		ns=$(sanitize_name "$testpath/$2")
 		SOURCEFILE=$ns.vala
 		SOURCEFILES="$SOURCEFILES $SOURCEFILE"
-	elif [ $GIRWRITERTEST -eq 1 ]; then
+	elif [ "$GIRWRITERTEST" -eq 1 ]; then
 		if [ "$1" = "Input:" ]; then
 			ns=$testpath
 			SOURCEFILE=$testpath.vala
-			cat <<EOF > $SOURCEFILE
+			cat <<EOF > "$SOURCEFILE"
 [CCode (cprefix = "Test", gir_namespace = "Test", gir_version = "1.2", lower_case_cprefix = "test_")]
 namespace Test {
 EOF
@@ -108,26 +118,26 @@
 	fi
 }
 
-function sourceend() {
-	if [ $INVALIDCODE -eq 1 ]; then
-		PACKAGEFLAGS=$([ -z "$PACKAGES" ] || echo $PACKAGES | xargs -n 1 echo -n " --pkg")
+sourceend() {
+	if [ "$INVALIDCODE" -eq 1 ]; then
+		PACKAGEFLAGS=$(package_flags)
 		echo '' > prepare
 		echo "$VALAC $VALAFLAGS $PACKAGEFLAGS -C $SOURCEFILE" > check
 		echo "RET=\$?" >> check
 		echo "if [ \$RET -ne 1 ]; then exit 1; fi" >> check
 		echo "exit 0" >> check
-	elif [ $GIRWRITERTEST -eq 1 ]; then
-		if [ $PART -eq 1 ]; then
-			echo "}" >> $SOURCEFILE
+	elif [ "$GIRWRITERTEST" -eq 1 ]; then
+		if [ "$PART" -eq 1 ]; then
+			echo "}" >> "$SOURCEFILE"
 		fi
-		PACKAGEFLAGS=$([ -z "$PACKAGES" ] || echo $PACKAGES | xargs -n 1 echo -n " --pkg")
+		PACKAGEFLAGS=$(package_flags)
 		echo "$VALAC $VALAFLAGS $PACKAGEFLAGS -C --library test -H test.h --gir Test-1.2.gir $ns.vala && tail -n +4 Test-1.2.gir|sed '\$d'|diff -wu Test-1.2.gir.ref -" > check
 	else
-		PACKAGEFLAGS=$([ -z "$PACKAGES" ] || echo $PACKAGES | xargs -n 1 echo -n " --pkg")
+		PACKAGEFLAGS=$(package_flags)
 		echo "$VALAC $VALAFLAGS $PACKAGEFLAGS -o $ns$EXEEXT $SOURCEFILE" >> prepare
-		if [ $DBUSTEST -eq 1 ]; then
+		if [ "$DBUSTEST" -eq 1 ]; then
 			echo "UPDATE_EXPECTED=$UPDATE_EXPECTED" >> prepare
-			if [ $ISSERVER -eq 1 ]; then
+			if [ "$ISSERVER" -eq 1 ]; then
 				echo "if [ -n \"$UPDATE_EXPECTED\" ]; then" >> prepare
 				echo "	cp -p ${SOURCEFILE%.*}.c $abs_srcdir/${testfile%.*}_server.c-expected" >> prepare
 				echo "elif [ -f $abs_srcdir/${testfile%.*}_server.c-expected ]; then" >> prepare
@@ -152,38 +162,40 @@
 unset SOURCEFILE
 
 testdir=_test.$$
-rm -rf ./$testdir
-mkdir $testdir
-cd $testdir
+rm -rf "./$testdir"
+mkdir "$testdir"
+cd "$testdir"
 
 case "$testfile" in
-*.gs)
-	SOURCEFILE=$testpath.gs
-	;&
-*.vala)
+*.gs|*.vala)
+	case "$testfile" in
+	*.gs)
+		SOURCEFILE=$testpath.gs
+		;;
+	esac
 	SOURCEFILE=${SOURCEFILE:-$testpath.vala}
-	cat "$abs_srcdir/$testfile" > ./$SOURCEFILE
-	PACKAGEFLAGS=$([ -z "$PACKAGES" ] || echo $PACKAGES | xargs -n 1 echo -n " --pkg")
-	$VALAC $VALAFLAGS $PACKAGEFLAGS -o $testpath$EXEEXT $SOURCEFILE
+	cat "$abs_srcdir/$testfile" > "./$SOURCEFILE"
+	PACKAGEFLAGS=$(package_flags)
+	$VALAC $VALAFLAGS $PACKAGEFLAGS -o "$testpath$EXEEXT" "$SOURCEFILE"
 	if [ -n "$UPDATE_EXPECTED" ]; then
-		cp -p ${SOURCEFILE%.*}.c $abs_srcdir/${testfile%.*}.c-expected
+		cp -p "${SOURCEFILE%.*}.c" "$abs_srcdir/${testfile%.*}.c-expected"
 		if [ -f test.h ]; then
-			cp -p test.h $abs_srcdir/${testfile%.*}.h-expected || exit 1
+			cp -p test.h "$abs_srcdir/${testfile%.*}.h-expected" || exit 1
 		fi
-	elif [ -f $abs_srcdir/${testfile%.*}.c-expected ]; then
-		diff -wu $abs_srcdir/${testfile%.*}.c-expected ${SOURCEFILE%.*}.c || exit 1
-		if [ -f $abs_srcdir/${testfile%.*}.h-expected ]; then
-			diff -wu $abs_srcdir/${testfile%.*}.h-expected test.h || exit 1
+	elif [ -f "$abs_srcdir/${testfile%.*}.c-expected" ]; then
+		diff -wu "$abs_srcdir/${testfile%.*}.c-expected" "${SOURCEFILE%.*}.c" || exit 1
+		if [ -f "$abs_srcdir/${testfile%.*}.h-expected" ]; then
+			diff -wu "$abs_srcdir/${testfile%.*}.h-expected" test.h || exit 1
 		fi
 	fi
-	./$testpath$EXEEXT
+	"./$testpath$EXEEXT"
 	;;
 *.gir)
 	SOURCEFILE=$testpath.gir
-	cat "$abs_srcdir/$testfile" > ./$SOURCEFILE
-	PACKAGEFLAGS=$([ -z "$PACKAGES" ] || echo $PACKAGES | xargs -n 1 echo -n " --pkg")
-	$VAPIGEN $VAPIGENFLAGS $PACKAGEFLAGS --library $testpath $SOURCEFILE || exit 1
-	tail -n +3 ${SOURCEFILE%.*}.vapi | diff -wu $abs_srcdir/${testfile%.*}.vapi-expected - || exit 1
+	cat "$abs_srcdir/$testfile" > "./$SOURCEFILE"
+	PACKAGEFLAGS=$(package_flags)
+	$VAPIGEN $VAPIGENFLAGS $PACKAGEFLAGS --library "$testpath" "$SOURCEFILE" || exit 1
+	tail -n +3 "${SOURCEFILE%.*}.vapi" | diff -wu "$abs_srcdir/${testfile%.*}.vapi-expected" - || exit 1
 	;;
 *.test)
 	rm -f prepare check
@@ -195,37 +207,41 @@
 	GIRWRITERTEST=0
 	DBUSTEST=0
 	ISSERVER=0
-	while IFS="" read -r line; do
-		if [ $PART -eq 0 ]; then
+	while IFS= read -r line; do
+		if [ "$PART" -eq 0 ]; then
 			if [ -n "$line" ]; then
 				testheader $line
 			else
 				PART=1
 			fi
 		else
-			if [ $INHEADER -eq 1 ]; then
+			if [ "$INHEADER" -eq 1 ]; then
 				if [ -n "$line" ]; then
 					sourceheader $line
 				else
 					INHEADER=0
 				fi
 			else
-				if echo "$line" | grep -q "^[A-Za-z]\+:"; then
+				if printf '%s\n' "$line" | grep -q '^[A-Za-z][A-Za-z]*:'; then
 					sourceend
-					PART=$(($PART + 1))
+					PART=$((PART + 1))
 					INHEADER=1
 					sourceheader $line
 				else
-					echo "$line" >> $SOURCEFILE
+					echo "$line" >> "$SOURCEFILE"
 				fi
 			fi
 		fi
 	done < "$abs_srcdir/$testfile"
 	sourceend
-	cat prepare check > $ns.check
-	$run_prefix bash $ns.check
+	cat prepare check > "$ns.check"
+	if [ -n "$run_prefix" ]; then
+		$run_prefix sh "$ns.check"
+	else
+		sh "$ns.check"
+	fi
 	;;
 esac
 
 cd ..
-rm -rf ./$testdir
+rm -rf "./$testdir"