diff --git a/src/ersky9x/board.h b/src/ersky9x/board.h
index 019b5cc5d..b0a69db23 100644
--- a/src/ersky9x/board.h
+++ b/src/ersky9x/board.h
@@ -548,7 +548,7 @@ extern uint32_t transSpeed;
 
 #define SD_GET_SPEED()                 (transSpeed)
 
-#define SD_GET_SIZE_MB()               (SD_GET_BLOCKNR() / 2)
+#define SD_GET_SIZE_MB()               (SD_GET_BLOCKNR() / 2048)
 
 //------------------------------------------------------------------------------