diff --git a/packages/browser-stdenv/build-aggregate.sh b/packages/browser-stdenv/build-aggregate.sh
index 2c81eff..295cdb1 100755
--- a/packages/browser-stdenv/build-aggregate.sh
+++ b/packages/browser-stdenv/build-aggregate.sh
@@ -1,5 +1,9 @@
 #!/bin/sh
 
+set -e
+
+cd "$(dirname "$0")"
+
 M=../../node_modules
 
 cat \
@@ -39,3 +43,5 @@ cp \
     $M/@syndicate-lang/ws-relay/dist/syndicate-ws-relay.min.js.map \
     $M/@syndicate-lang/compiler/dist/syndicate-compiler.min.js.map \
     .
+
+echo $(date) $(pwd) 'build complete.'
diff --git a/packages/browser-stdenv/package.json b/packages/browser-stdenv/package.json
index 5c3840c..deedea3 100644
--- a/packages/browser-stdenv/package.json
+++ b/packages/browser-stdenv/package.json
@@ -15,6 +15,7 @@
   "author": "Tony Garnock-Jones <tonyg@leastfixedpoint.com>",
   "scripts": {
     "prepare": "./build-aggregate.sh",
+    "prepare:watch": "cd ..; exec inotifytest browser-stdenv/build-aggregate.sh",
     "clean": "rm -rf index.js index.min.js *.js.map",
     "veryclean": "yarn run clean && rm -rf node_modules"
   },
diff --git a/watchall b/watchall
index 7976496..c1069c3 100755
--- a/watchall
+++ b/watchall
@@ -16,12 +16,14 @@ open() {
 
 for d in packages/*/tsconfig.json
 do
-    open "cd $(dirname $d); yarn compile:watch"
+    open "cd $(dirname $d); exec yarn compile:watch"
 done
 
 for d in packages/*/rollup.config.js
 do
-    open "cd $(dirname $d); yarn rollup:watch"
+    open "cd $(dirname $d); exec yarn rollup:watch"
 done
 
+open "cd packages/browser-stdenv; exec yarn prepare:watch"
+
 tmux select-layout even-vertical