diff --git a/src/trunnel/README b/src/trunnel/README
new file mode 100644
index 0000000000..383272cf78
--- /dev/null
+++ b/src/trunnel/README
@@ -0,0 +1,10 @@
+This directory contains code for use with, and code made by, the
+automatic code generation tool "Trunnel".
+
+The .trunnel files are the inputs here; the .c and .h files are the outputs.
+To regenerate the .c and .h files, run "scripts/codegen/run_trunnel.sh".
+
+For the Trunnel source code, and more documentation about using Trunnel,
+see https://gitweb.torproject.org/trunnel.git , especially
+    https://gitweb.torproject.org/trunnel.git/tree/README
+and https://gitweb.torproject.org/trunnel.git/tree/doc/trunnel.md
diff --git a/src/trunnel/include.am b/src/trunnel/include.am
index 9bf37fe58b..b1448b7cb2 100644
--- a/src/trunnel/include.am
+++ b/src/trunnel/include.am
@@ -36,3 +36,7 @@ src_trunnel_libor_trunnel_testing_a_CPPFLAGS = -DTRUNNEL_LOCAL_H $(AM_CPPFLAGS)
 src_trunnel_libor_trunnel_testing_a_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
 
 noinst_HEADERS+= $(TRUNNELHEADERS)
+
+EXTRA_DIST += \
+	src/trunnel/README
+