diff --git a/abump.in b/abump.in
index 6cb6c87..ab92179 100644
--- a/abump.in
+++ b/abump.in
@@ -44,16 +44,21 @@ do_bump() {
 		a=$(aports_buildscript "$name" ) \
 			|| die "can't find APKBUILD for $name"
 
-		# verify APKBUILD
-		. "$a" || exit 1
-		name=${name#*/}
-		[ "$pkgname" = "$name" ] \
-			|| die "APKBUILD has different \$pkgname for $name"
-		type package | grep -q function \
-			|| die "missing package() for $name"
-		if [ "$pkgver" = "$ver" ] && git diff-index --quiet HEAD -- "$a"; then
-			die "version is already $ver"
-		fi
+		# sourcing APKBUILDs should not affect the environment of abump
+		# so do that in a subshell, along with any checks that need the
+		# information from the APKBUILD.
+		(
+			# verify APKBUILD
+			. "$a" || exit 1
+			name=${name#*/}
+			[ "$pkgname" = "$name" ] \
+				|| die "APKBUILD has different \$pkgname for $name"
+			type package | grep -q function \
+				|| die "missing package() for $name"
+			if [ "$pkgver" = "$ver" ] && git diff-index --quiet HEAD -- "$a"; then
+				die "version is already $ver"
+			fi
+		)
 
 		cd "${a%/*}"
 		section=${PWD%/*}