diff --git a/src/runtime/runtime_esp32.go b/src/runtime/runtime_esp32.go
index 3075744c..0543a4bd 100644
--- a/src/runtime/runtime_esp32.go
+++ b/src/runtime/runtime_esp32.go
@@ -13,6 +13,10 @@ import (
 // set.
 //export main
 func main() {
+	// Disable the protection on the watchdog timer (needed when started from
+	// the bootloader).
+	esp.RTCCNTL.WDTWPROTECT.Set(0x050D83AA1)
+
 	// Disable both watchdog timers that are enabled by default on startup.
 	// Note that these watchdogs can be protected, but the ROM bootloader
 	// doesn't seem to protect them.