diff --git a/config/impl.go b/config/impl.go
index 1d28de8..914fffb 100644
--- a/config/impl.go
+++ b/config/impl.go
@@ -6,6 +6,7 @@ import "sync"
 import "slices"
 import "path/filepath"
 import "github.com/fsnotify/fsnotify"
+import "git.tebibyte.media/tomo/tomo"
 import "git.tebibyte.media/tomo/tomo/event"
 
 // Goroutine model:
@@ -67,15 +68,19 @@ func (this *config) lockAndProcessEvent (event fsnotify.Event) {
 	if _, ok := this.paths.watching[event.Name]; !ok { return }
 
 	if event.Name == this.paths.user {
+		previousUser := this.data.user
 		this.reloadUser()
+		newUser := this.data.user
+		this.processUserDiff(newUser.Diff(previousUser))
 	} else {
 		index := slices.Index(this.paths.system, event.Name)
 		if index > 0 {
+			previousSystem := this.data.system[index]
 			this.reloadSystem(index)
+			newSystem := this.data.system[index]
+			this.processSystemDiff(index, diffValueMaps(newSystem, previousSystem))
 		}
 	}
-
-	// TODO diff and call event handler if changed
 }
 
 func (this *config) init () error {
@@ -178,7 +183,7 @@ func (this *config) processSystemDiff (index int, changed map[string] struct { }
 
 func (this *config) broadcastChange (key string) {
 	for _, listener := range this.on.change.Listeners() {
-		listener(key)
+		tomo.Do(func () { listener(key) })
 	}
 }