diff --git a/build-aux/license-check.sh b/build-aux/license-check.sh
index f352e1c8..ce1f60c5 100644
--- a/build-aux/license-check.sh
+++ b/build-aux/license-check.sh
@@ -11,7 +11,7 @@
 # when .git isn't available, from files extracted from a release tarball
 # (in case of a release tarball, the tree must be clean of any extra files).
 #
-# NOTE: This uses grep and xargs with options that aren't in POSIX.
+# NOTE: This relies on non-POSIX xargs -0. It's supported on GNU and *BSDs.
 #
 ###############################################################################
 #
@@ -99,11 +99,12 @@ FILES=$(printf '%s\n' "$FILES" | sort)
 
 
 # Find the tagged files.
-TAGGED=$(printf '%s\n' "$FILES" | xargs -r -d '\n' grep -l "$SPDX_LI")
+TAGGED=$(printf '%s\n' "$FILES" \
+	| tr '\n' '\000' | xargs -0r grep -l "$SPDX_LI")
 
 # Find the tagged 0BSD files.
 TAGGED_0BSD=$(printf '%s\n' "$TAGGED" \
-	| xargs -r -d '\n' grep -l "$SPDX_LI 0BSD")
+	| tr '\n' '\000' | xargs -0r grep -l "$SPDX_LI 0BSD")
 
 # Find the tagged non-0BSD files, that is, remove the 0BSD-tagged files
 # from the list of tagged files.
@@ -125,8 +126,8 @@ FILES=$(printf '%s\n' "$FILES" | grep -Ev \
 # FIXME: Allow untagged translations if they have a public domain notice.
 # These are old translations that haven't been updated after 2024-02-14.
 # Eventually these should go away.
-PD_PO=$(printf '%s\n' "$FILES" | grep '\.po$' | \
-	xargs -r -d '\n' grep -Fl '# This file is put in the public domain.')
+PD_PO=$(printf '%s\n' "$FILES" | grep '\.po$' | tr '\n' '\000' \
+	| xargs -0r grep -Fl '# This file is put in the public domain.')
 
 if test -n "$PD_PO"; then
 	# Remove the public domain .po files from the list.