1 files changed, 1 insertions, 1 deletions

diff --git a/keyboards/lets_split/rules.mk b/keyboards/lets_split/rules.mk
index 79860ea35..43eff99e7 100644
--- a/keyboards/lets_split/rules.mk
+++ b/keyboards/lets_split/rules.mk
@@ -78,7 +78,7 @@ CUSTOM_MATRIX = yes
 avrdude: build
         ls /dev/tty* > /tmp/1; \
         echo "Reset your Pro Micro now"; \
-        while [[ -z $$USB ]]; do \
+        while [ -z $$USB ]; do \
           sleep 1; \
           ls /dev/tty* > /tmp/2; \
           USB=`diff /tmp/1 /tmp/2 | grep -o '/dev/tty.*'`; \