diff --git a/lib/hal/HalPowerManager.cpp b/lib/hal/HalPowerManager.cpp
index 790c7c05..78f0018f 100644
--- a/lib/hal/HalPowerManager.cpp
+++ b/lib/hal/HalPowerManager.cpp
@@ -66,6 +66,15 @@ void HalPowerManager::startDeepSleep(HalGPIO& gpio) const {
     delay(50);
     gpio.update();
   }
+
+#ifdef ENABLE_SERIAL_LOG
+  // Tear down HWCDC so the host sees a clean disconnect and the peripheral
+  // doesn't hold power domains that interfere with USB-powered GPIO wake.
+  // logSerial is the raw HWCDC reference; Serial is the MySerialImpl proxy
+  // (which doesn't expose end()).
+  logSerial.end();
+#endif
+
   // Pre-sleep routines from the original firmware
   // GPIO13 is connected to battery latch MOSFET, we need to make sure it's low during sleep
   // Note that this means the MCU will be completely powered off during sleep, including RTC
diff --git a/src/main.cpp b/src/main.cpp
index 6c601ab9..3b7e7c9e 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -13,6 +13,7 @@
 #include <I18n.h>
 #include <Logging.h>
 #include <SPI.h>
+#include <WiFi.h>
 #include <builtinFonts/all.h>
 
 #include <cstring>
@@ -214,6 +215,13 @@ void enterDeepSleep() {
 
   activityManager.goToSleep();
 
+  // Tear down WiFi so the modem power domain isn't held alive across deep sleep.
+  // Wake from deep sleep is effectively a chip reset, so no state needs to survive.
+  if (WiFi.getMode() != WIFI_MODE_NULL) {
+    WiFi.disconnect(true);
+    WiFi.mode(WIFI_OFF);
+  }
+
   halTiltSensor.deepSleep();
   display.deepSleep();
   LOG_DBG("MAIN", "Entering deep sleep");