diff --git a/gateware/icE1usb/Makefile b/gateware/icE1usb/Makefile
index 759896f..0904660 100644
--- a/gateware/icE1usb/Makefile
+++ b/gateware/icE1usb/Makefile
@@ -40,7 +40,7 @@
 NEXTPNR_ARGS = --pre-pack data/clocks.py --no-promote-globals --seed 2
 
 # Include default rules
-NO2BUILD_DIR := ../build
+NO2BUILD_DIR ?= ../build
 include $(NO2BUILD_DIR)/project-rules.mk
 
 # Custom rules