diff --git a/test.bash b/test.bash
index f94f4d4e..174236e8 100755
--- a/test.bash
+++ b/test.bash
@@ -1,4 +1,7 @@
 #!/bin/bash
+#
+# test.bash runs the gocryptfs test suite against $TMPDIR,
+# or, if unset, /var/tmp.
 
 set -eu
 
@@ -72,6 +75,9 @@ else
 	echo "shellcheck not installed - skipping"
 fi
 
+echo -n "Testing on TMPDIR=$TMPDIR, filesystem: "
+findmnt --noheadings --target "$TESTDIR" --output FSTYPE,OPTIONS || true
+
 EXTRA_ARGS=""
 if [[ $VERBOSE -eq 1 ]]; then
 	# Disabling parallelism disables per-package output buffering, hence enabling