diff --git a/ports/zephyr-cp/prj.conf b/ports/zephyr-cp/prj.conf
index be6e22c8fa8..574f207c5a4 100644
--- a/ports/zephyr-cp/prj.conf
+++ b/ports/zephyr-cp/prj.conf
@@ -117,3 +117,9 @@ CONFIG_BT_MAX_PAIRED=3
 # region it does not recognise instead, so first boot after a layout change
 # recovers on its own rather than needing a manual erase.
 CONFIG_NVS_INIT_BAD_MEMORY_REGION=y
+
+# The rpi_pico UDC driver's internal thread defaults to 512 bytes, which
+# overflows once USB is servicing traffic alongside the WiFi/BT gSPI bus --
+# the board drops off USB mid-run ("USB device stack error" on reset). This
+# was previously only raised in debug.conf, so release builds still crashed.
+CONFIG_UDC_RPI_PICO_STACK_SIZE=2048