diff --git a/py/circuitpy_mpconfig.mk b/py/circuitpy_mpconfig.mk
index 496ce918ba..fea1f937ec 100644
--- a/py/circuitpy_mpconfig.mk
+++ b/py/circuitpy_mpconfig.mk
@@ -322,8 +322,10 @@ CFLAGS += -DCIRCUITPY_TOUCHIO=$(CIRCUITPY_TOUCHIO)
 CIRCUITPY_UHEAP ?= 0
 CFLAGS += -DCIRCUITPY_UHEAP=$(CIRCUITPY_UHEAP)
 
+# Disable by default for now, until we have dynamic enabling.
+CIRCUITPY_USB_CDC ?= 0
 # Secondary CDC is usually available if there are at least 8 endpoints.
-CIRCUITPY_USB_CDC ?= $(shell expr $(USB_NUM_EP) '>=' 8)
+#CIRCUITPY_USB_CDC ?= $(shell expr $(USB_NUM_EP) '>=' 8)
 CFLAGS += -DCIRCUITPY_USB_CDC=$(CIRCUITPY_USB_CDC)
 
 CIRCUITPY_USB_HID ?= 1