diff --git a/include/mmc.h b/include/mmc.h
index 229d494ff76de458e7150f0bac907c1cb6077c26..2dc69abb68e9fc3c1909cbfceb894055947cd24c 100644
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -47,7 +47,7 @@
 
 #define SD_DATA_4BIT	0x00040000
 
-#define IS_SD(x) (mmc->version & SD_VERSION_SD)
+#define IS_SD(x) (x->version & SD_VERSION_SD)
 
 #define MMC_DATA_READ		1
 #define MMC_DATA_WRITE		2