diff --git a/tests/len2elen.sh b/tests/len2elen.sh
new file mode 100755
index 0000000..e101277
--- /dev/null
+++ b/tests/len2elen.sh
@@ -0,0 +1,29 @@
+#!/bin/bash -eu
+#
+# Check plaintext file name length -> encrypted file name length relation
+#
+# Part of the gocryptfs test suite
+# https://nuetzlich.net/gocryptfs/
+
+NAME="x"
+LEN=0
+
+if [[ ! -f a/gocryptfs.conf ]] ; then
+	echo "fatal: must have gocryptfs dir 'a' mounted at 'b'"
+	exit 1
+fi
+if ! mountpoint b > /dev/null ; then
+	echo "fatal: must have gocryptfs dir 'a' mounted at 'b'"
+	exit 1
+fi
+
+rm -f b/*
+
+while [[ $LEN -le 255 ]]; do
+	touch b/$NAME || break
+	ELEN=$(ls a | wc -L)
+	echo $LEN $ELEN
+	rm b/$NAME
+	NAME="${NAME}x"
+	LEN=${#NAME}
+done