diff --git a/Sources/removemacai/App/Pages.swift b/Sources/removemacai/App/Pages.swift
index aadf4d3..57df695 100644
--- a/Sources/removemacai/App/Pages.swift
+++ b/Sources/removemacai/App/Pages.swift
@@ -300,13 +300,16 @@ struct BackgroundView: View {
               Text(item.label).font(.caption.monospaced()).foregroundStyle(.secondary)
               Text(item.program).font(.caption2.monospaced()).foregroundStyle(.tertiary)
                 .lineLimit(1).truncationMode(.middle)
+              if let warning = item.warning {
+                Label(warning, systemImage: "exclamationmark.triangle").font(.caption).foregroundStyle(.orange)
+              }
             }
           }
           .toggleStyle(.switch)
           .disabled(model.backgroundBusy)
         }
       } header: {
-        Text("Updaters, helpers and agents other apps installed. They run whether or not their app is open. Switching one off takes effect at once.")
+        Text("Updaters, helpers and agents other apps installed. They run whether or not their app is open. Switching one off takes effect at once. Updaters are safe to switch off; a helper can be what makes its app work, such as a VPN or Docker.")
           .font(.body).foregroundStyle(.secondary).textCase(nil)
       } footer: {
         Footer("Items marked All users ask for your password. Apple's own background services are protected by System Integrity Protection, so RemoveMacAI leaves them alone.")
diff --git a/Sources/removemacai/BackgroundItems.swift b/Sources/removemacai/BackgroundItems.swift
index ca04c1b..5ebdf0a 100644
--- a/Sources/removemacai/BackgroundItems.swift
+++ b/Sources/removemacai/BackgroundItems.swift
@@ -16,6 +16,18 @@ struct BackgroundItem: Identifiable, Hashable {
 
   static let interpreters: Set<String> = ["sh", "bash", "zsh", "python3", "python", "node", "osascript", "perl", "ruby"]
 
+  /// Whether it only keeps its app up to date, judged by its label and the
+  /// name of what it runs. Anything else (a VPN, Docker's socket, a sync or
+  /// licensing helper) can be what makes its app work, so it gets a warning.
+  var isUpdater: Bool {
+    [label, (program as NSString).lastPathComponent].contains { $0.lowercased().contains("update") }
+  }
+
+  /// What switching it off can break, or nil for an updater.
+  var warning: String? {
+    isUpdater ? nil : "Not an updater. Turning it off can stop \(owner) working."
+  }
+
   /// The app or program it runs, as people know it.
   var owner: String {
     if let app = program.split(separator: "/").first(where: { $0.hasSuffix(".app") }) {
diff --git a/Sources/removemacai/SelfTest.swift b/Sources/removemacai/SelfTest.swift
index e260482..0061e53 100644
--- a/Sources/removemacai/SelfTest.swift
+++ b/Sources/removemacai/SelfTest.swift
@@ -217,6 +217,15 @@ func selfTest() -> Bool {
     program: "/Library/PrivilegedHelperTools/dev.orbstack.OrbStack.privhelper", system: true)
   check(script.owner == "sync.sh" && helper.owner == "OrbStack", "background items are named after what they run")
 
+  let updater = BackgroundItem(label: "com.google.GoogleUpdater.wake", plist: "",
+    program: "/Users/x/Library/Application Support/Google/GoogleUpdater/Current/GoogleUpdater.app/Contents/MacOS/GoogleUpdater",
+    system: false)
+  check(updater.isUpdater && updater.warning == nil && !helper.isUpdater && helper.warning != nil,
+    "helpers that aren't updaters carry a warning")
+  let vpn = BackgroundItem(label: "com.example.vpn", plist: "", program: "/Library/Example Updates/vpnd",
+    arguments: ["/Library/Example Updates/vpnd", "--check-updates"], system: true)
+  check(!vpn.isUpdater && vpn.warning != nil, "an unrelated mention of updates keeps the warning")
+
   print(failed == 0 ? Term.green("all checks passed") : Term.red("\(failed) failed"))
   return failed == 0
 }
diff --git a/Sources/removemacai/TweakCommands.swift b/Sources/removemacai/TweakCommands.swift
index 0c11e7d..dc1a87b 100644
--- a/Sources/removemacai/TweakCommands.swift
+++ b/Sources/removemacai/TweakCommands.swift
@@ -142,10 +142,14 @@ enum TweakCommands {
       }
       print(Term.bold("Background items from other apps"))
       for item in items {
-        let state = BackgroundItems.isDisabled(item, labels) ? Term.dim("off") : Term.green("on")
-        print("  " + Term.pad(item.label, 48) + Term.pad(item.owner, 22) + state + (item.system ? Term.dim("  (all users)") : ""))
+        let off = BackgroundItems.isDisabled(item, labels)
+        let state = off ? Term.dim(Term.pad("off", 5)) : Term.green(Term.pad("on", 5))
+        let kind = item.isUpdater ? Term.dim("updater") : Term.yellow("helper")
+        print("  " + Term.pad(item.label, 48) + Term.pad(item.owner, 22) + state + kind
+          + (item.system ? Term.dim("  (all users)") : ""))
       }
       print()
+      print(Term.dim("Turning off a helper can stop its app working, for example a VPN or Docker."))
       print(Term.dim("Turn one off with: removemacai background off <label>"))
       return true
     }
@@ -155,6 +159,9 @@ enum TweakCommands {
       Term.fail("there is no background item called \"\(name)\"")
     }
     guard !chosen.isEmpty else { Term.fail("name the items, as listed by: removemacai background") }
+    if action == "off" {
+      for item in chosen { if let warning = item.warning { print(Term.yellow("!") + " \(item.label): " + warning) } }
+    }
     if !yes {
       guard isatty(STDIN_FILENO) == 1 else { Term.fail("run it in a terminal, or add --yes") }
       let verb = action == "off" ? "Turn off" : "Turn on"