diff --git a/platformio.ini b/platformio.ini
index 96c25a6d..89110f28 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -27,7 +27,7 @@ framework = arduino
 upload_protocol = teensy-cli
 test_build_src = true
 board_build.f_cpu = 24000000L
-build_flags = -D ACS_SIM -D VERBOSE -D TEENSY_OPT_SMALLEST_CODE
+build_flags = -D ACS_SIM -D VERBOSE -D TEENSY_OPT_SMALLEST_CODE -D SIMULATOR
 lib_ldf_mode = deep
 monitor_filters = default, log2file