diff --git a/mendel/gcode.c b/mendel/gcode.c
index 6d06e08..03491e8 100644
--- a/mendel/gcode.c
+++ b/mendel/gcode.c
@@ -312,7 +312,7 @@ void scan_char(uint8_t c) {
 					) {
 					process_gcode_command(&next_target);
 
-					serial_writestr_P(PSTR("OK\n"));
+					serial_writestr_P(PSTR("ok\n"));
 
 					// expect next line number
 					next_target.N_expected++;