diff --git a/update-whatprovides-db.sh b/update-whatprovides-db.sh
index e5975ed..d8256fc 100755
--- a/update-whatprovides-db.sh
+++ b/update-whatprovides-db.sh
@@ -6,10 +6,12 @@
 
 set -e -u
 
+: "${TERMUX_PREFIX:="/data/data/com.termux/files/usr"}"
+
 list_files() {
 	dpkg-deb -c "${1}" | grep -o "/data/data/com\.termux/files/.\+" \
 		| sed -E 's@(.*) ->..*@\1@g;s@/$@@g' \
-		| xargs -rd\\n realpath -sm --relative-base=$TERMUX_PREFIX --
+		| xargs -rd\\n realpath -sm --relative-base="$TERMUX_PREFIX" --
 }
 
 write_sql_script() {