diff --git a/modules/power/module.json b/modules/power/module.json
index e35522a..3472f24 100644
--- a/modules/power/module.json
+++ b/modules/power/module.json
@@ -213,7 +213,7 @@
       "type": "file",
       "path": "/etc/udev/rules.d/90-mesh-power.rules",
       "mode": "0644",
-      "content": "# Written by the mesh (module power, novox/hq ADR 0211). Replaced on every push.\n# A change of a power supply runs the power source's moment once (the runner says nothing twice).\nSUBSYSTEM==\"power_supply\", ACTION==\"change\", RUN+=\"/usr/bin/systemctl --no-block start mesh-power-supply.service\"\n"
+      "content": "# Written by the mesh (module power, novox/hq ADR 0211). Replaced on every push.\n# Only the charger's change can switch the machine between mains and battery. A battery reports its\n# level many times a minute, and USB-C supplies come and go; matching them started the supply unit\n# every second or two on the laptop.\nSUBSYSTEM==\"power_supply\", ACTION==\"change\", ATTR{type}==\"Mains\", RUN+=\"/usr/bin/systemctl --no-block start mesh-power-supply.service\"\n"
     },
     {
       "id": "after-boot",