diff --git a/target/linux/ramips/files/drivers/mmc/host/mtk-mmc/dbg.c b/target/linux/ramips/files/drivers/mmc/host/mtk-mmc/dbg.c
index d897b12163..fc5f1e4985 100644
--- a/target/linux/ramips/files/drivers/mmc/host/mtk-mmc/dbg.c
+++ b/target/linux/ramips/files/drivers/mmc/host/mtk-mmc/dbg.c
@@ -48,8 +48,6 @@
 #include "mt6575_sd.h"
 #include <linux/seq_file.h>
 
-static char cmd_buf[256];
-
 /* for debug zone */
 unsigned int sd_debug_zone[4] = {
 	0,
@@ -59,6 +57,9 @@ unsigned int sd_debug_zone[4] = {
 };
 
 #if defined(MT6575_SD_DEBUG)
+
+static char cmd_buf[256];
+
 /* for driver profile */
 #define TICKS_ONE_MS  (13000)
 u32 gpt_enable;