diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 0000000..955ed9b
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,3 @@
+datadir/
+LICENSE
+README.md
diff --git a/scripts/join-insv b/scripts/join-insv
index bab0914..4f3a9a6 100755
--- a/scripts/join-insv
+++ b/scripts/join-insv
@@ -51,7 +51,7 @@ join_insv() {
   local outfile="$2"
   shift 2
 
-  local tmpfile="_tmp.${outfile}"
+  local tmpfile="${outfile}"_tmp_.mp4
   local file_list
   file_list="_list.txt"