diff --git a/changes/bug13111-generate-keys-on-empty-file b/changes/bug13111-generate-keys-on-empty-file
index 345e87ab75..20c10c7443 100644
--- a/changes/bug13111-generate-keys-on-empty-file
+++ b/changes/bug13111-generate-keys-on-empty-file
@@ -1,17 +1,23 @@
-  o Minor bugfixes
+  o Minor bugfixes (file handling):
     - Stop failing when key files are zero-length. Instead, generate new
       keys, and overwrite the empty key files.
-      Fixes bug 13111.
+      Fixes bug 13111. Patch by "teor".
     - Stop generating a fresh .old RSA key file when the .old file is missing.
-      Fixed as part of bug 13111.
     - Avoid overwriting .old key files with empty key files.
-      Fixed as part of bug 13111.
     - Stop crashing when a NULL filename is passed to file_status().
-      Fixed as part of bug 13111.
+      Fixed as part of bug 13111. Patches by "teor".
 
-  o Minor enhancements:
+  o Minor enhancements (file handling):
     - Skip loading zero-length extra info store, router store, stats, state,
       and key files.
-      Implemented with bug 13111.
     - Return FN_ERROR when a zero-length filename is passed to file_status().
-      Fixed as part of bug 13111.
+      Fixed as part of bug 13111. Patches by "teor".
+
+  o Minor enhancements (testing):
+    - Test that tor does not fail when key files are zero-length.
+      Check that tor generates new keys, and overwrites the empty key files.
+    - Test that tor generates new keys when keys are missing (existing
+      behaviour).
+    - Test that tor does not overwrite key files that already contain data
+      (existing behaviour).
+      Tests bug 13111. Patch by "teor".
diff --git a/src/test/include.am b/src/test/include.am
index d7a647940b..4518f8fb8f 100644
--- a/src/test/include.am
+++ b/src/test/include.am
@@ -120,9 +120,11 @@ if USEPYTHON
 	./src/test/test-bt-cl assert | $(PYTHON) $(top_srcdir)/src/test/bt_test.py
 	./src/test/test-bt-cl crash | $(PYTHON) $(top_srcdir)/src/test/bt_test.py
 endif
+	./src/test/zero_length_keys.sh
 
 EXTRA_DIST += \
 	src/test/bt_test.py \
 	src/test/ntor_ref.py \
 	src/test/slownacl_curve25519.py \
-	src/test/test_cmdline_args.py
+	src/test/test_cmdline_args.py \
+	src/test/zero_length_keys.sh
diff --git a/src/test/zero_length_keys.sh b/src/test/zero_length_keys.sh
new file mode 100755
index 0000000000..e7cb900cec
--- /dev/null
+++ b/src/test/zero_length_keys.sh
@@ -0,0 +1,113 @@
+#!/bin/sh
+# Check that tor regenerates keys when key files are zero-length
+# Test for bug #13111 - Tor fails to start if onion keys are zero length
+#
+# Usage:
+#  ./zero_length_keys.sh
+#    Run all the tests below
+#  ./zero_length_keys.sh -z
+#    Check tor will launch and regenerate zero-length keys
+#  ./zero_length_keys.sh -d
+#    Check tor regenerates deleted keys (existing behaviour)
+#  ./zero_length_keys.sh -e
+#    Check tor does not overwrite existing keys (existing behaviour)
+#
+# Exit Statuses:
+#  -2: test failed - tor did not generate the key files on first run
+#  -1: a command failed - the test could not be completed
+#   0: test succeeded - tor regenerated/kept the files
+#   1: test failed - tor did not regenerate/keep the files
+#
+
+if [ $# -lt 1 ]; then
+  echo "Testing that tor correctly handles zero-length keys"
+  "$0" -z && "$0" -d && "$0" -e
+  exit $?
+fi
+
+export DATA_DIR=`mktemp -d -t tor_zero_length_keys`
+TOR="src/or/tor --hush --DisableNetwork 1 --ShutdownWaitLength 0 --ORPort 12345"
+
+if [ -s "$DATA_DIR"/keys/secret_id_key -a -s "$DATA_DIR"/keys/secret_onion_key -a -s "$DATA_DIR"/keys/secret_onion_key_ntor ]; then
+  echo "Failure: Previous tor keys present in tor data directory"
+  exit -1
+else
+  echo "Generating initial tor keys"
+  $TOR --DataDirectory "$DATA_DIR" --PidFile "$DATA_DIR"/pid &
+  TOR_PID=$!
+  # generate SIGTERM, hopefully after the keys have been regenerated
+  sleep 5
+  kill $TOR_PID
+  wait $TOR_PID
+
+  # tor must successfully generate non-zero-length key files
+  if [ -s "$DATA_DIR"/keys/secret_id_key -a -s "$DATA_DIR"/keys/secret_onion_key -a -s "$DATA_DIR"/keys/secret_onion_key_ntor ]; then
+    true #echo "tor generated the initial key files"
+  else
+    echo "Failure: tor failed to generate the initial key files"
+    exit -2
+  fi
+fi
+
+#ls -lh  "$DATA_DIR"/keys/ || exit -1
+
+# backup and keep/delete/create zero-length files for the keys
+
+FILE_DESC="keeps existing"
+# make a backup
+cp -r "$DATA_DIR"/keys "$DATA_DIR"/keys.old
+
+# delete keys for -d or -z
+if [ "$1" != "-e" ]; then
+  FILE_DESC="regenerates deleted"
+  rm "$DATA_DIR"/keys/secret_id_key || exit -1
+  rm "$DATA_DIR"/keys/secret_onion_key || exit -1
+  rm "$DATA_DIR"/keys/secret_onion_key_ntor || exit -1
+fi
+
+# create empty files for -z
+if [ "$1" == "-z" ]; then
+  FILE_DESC="regenerates zero-length"
+  touch "$DATA_DIR"/keys/secret_id_key || exit -1
+  touch "$DATA_DIR"/keys/secret_onion_key || exit -1
+  touch "$DATA_DIR"/keys/secret_onion_key_ntor || exit -1
+fi
+
+echo "Running tor again to check if it $FILE_DESC keys"
+$TOR --DataDirectory "$DATA_DIR" --PidFile "$DATA_DIR"/pid &
+TOR_PID=$!
+# generate SIGTERM, hopefully after the keys have been regenerated
+sleep 5
+kill $TOR_PID
+wait $TOR_PID
+
+#ls -lh "$DATA_DIR"/keys/ || exit -1
+
+# tor must always have non-zero-length key files
+if [ -s "$DATA_DIR"/keys/secret_id_key -a -s "$DATA_DIR"/keys/secret_onion_key -a -s "$DATA_DIR"/keys/secret_onion_key_ntor ]; then
+  # check if the keys are different to the old ones
+  diff -q -r "$DATA_DIR"/keys "$DATA_DIR"/keys.old > /dev/null
+  SAME_KEYS=$?
+  # if we're not testing existing keys,
+  # the current keys should be different to the old ones
+  if [ "$1" != "-e" ]; then
+    if [ $SAME_KEYS -ne 0 ]; then
+      echo "Success: test that tor $FILE_DESC key files: different keys"
+      exit 0
+    else
+      echo "Failure: test that tor $FILE_DESC key files: same keys"
+      exit 1
+    fi
+  else #[ "$1" == "-e" ]; then
+    if [ $SAME_KEYS -eq 0 ]; then
+      echo "Success: test that tor $FILE_DESC key files: same keys"
+      exit 0
+    else
+      echo "Failure: test that tor $FILE_DESC key files: different keys"
+      exit 1
+    fi
+  fi
+else
+  echo "Failure: test that tor $FILE_DESC key files: no key files"
+  exit 1
+fi