diff --git a/hardware/sdcard/diskio.c b/hardware/sdcard/diskio.c
index c9644a1..b3e4541 100755
--- a/hardware/sdcard/diskio.c
+++ b/hardware/sdcard/diskio.c
@@ -22,7 +22,7 @@
 /* Port controls  (Platform dependent) */
 #define CS_LOW()	SD_CS_PORT &= ~(_BV(SD_CS_PIN))			/* CS=low */
 #define	CS_HIGH()	SD_CS_PORT |= _BV(SD_CS_PIN)			/* CS=high */
-#define MMC_CD		(config_invert_sddetect == false ? (SD_DETECT_INPUT & _BV(SD_DETECT_PIN)) : (SD_DETECT_INPUT & ~_BV(SD_DETECT_PIN)))	/* Card detected.   yes:true, no:false, default:true */
+#define MMC_CD		(config_invert_sddetect == false ? (SD_DETECT_INPUT & _BV(SD_DETECT_PIN)) : ((SD_DETECT_INPUT & _BV(SD_DETECT_PIN)) == 0))	/* Card detected.   yes:true, no:false, default:true */
 #define MMC_WP		(false)				/* Write protected. yes:true, no:false, default:false */
 #define	FCLK_SLOW()	SPCR = 0x52		/* Set slow clock (F_CPU / 64) */
 #define	FCLK_FAST()	SPCR = 0x50		/* Set fast clock (F_CPU / 2) */
@@ -579,6 +579,6 @@ void disk_timerproc(void) {
 	} else {
 		s |= (STA_NODISK | STA_NOINIT); /* Socket empty */
 	}							
-	
+
 	Stat = s;				/* Update MMC status */
 }