diff --git a/etc/kaleidoscope-builder.conf b/etc/kaleidoscope-builder.conf
index 4c35fd6d..ff955a22 100644
--- a/etc/kaleidoscope-builder.conf
+++ b/etc/kaleidoscope-builder.conf
@@ -11,7 +11,7 @@
 
 : "${BOARD:=model01}"
 
-if [ -z "${ARCH}" ]; then
+if [[  -z "${ARCH}" && -n "${FQBN}" ]]; then
    ARCH=$(echo "${FQBN}" | sed -n -e 's/^[^:]\+:\([^:]\+\).*/\1/p')
 fi