diff --git a/firmware/hw_layer/mmc_card.cpp b/firmware/hw_layer/mmc_card.cpp
index 5830b7164f..066edde112 100644
--- a/firmware/hw_layer/mmc_card.cpp
+++ b/firmware/hw_layer/mmc_card.cpp
@@ -47,6 +47,7 @@ static bool fs_ready = false;
 
 EXTERN_ENGINE;
 
+// at about 20Hz we write about 2Kb per second, looks like we flush once every ~2 seconds
 #define F_SYNC_FREQUENCY 10
 
 static int totalLoggedBytes = 0;