diff --git a/source/fatfs/diskio.c b/source/fatfs/diskio.c
index 9e1f6df..2b62445 100644
--- a/source/fatfs/diskio.c
+++ b/source/fatfs/diskio.c
@@ -134,12 +134,14 @@ DSTATUS disk_initialize (
             return RES_PARERR;
     } else if (pdrv < 4) {
         nand_type_sys = CheckNandType(NAND_SYSNAND);
+        if (!nand_type_sys) return RES_PARERR;
     } else if (pdrv < 7) {
         nand_type_emu = CheckNandType(NAND_EMUNAND);
+        if (!nand_type_emu) return RES_PARERR;
     } else if (pdrv < 10) {
-        if (!GetMountState())
-            return RES_PARERR;
+        if (!GetMountState()) return RES_PARERR;
         nand_type_img = CheckNandType(NAND_IMGNAND);
+        if (!nand_type_img) return RES_PARERR;
     }
 	return RES_OK;
 }
diff --git a/source/fs.c b/source/fs.c
index 3964918..c7fc668 100644
--- a/source/fs.c
+++ b/source/fs.c
@@ -35,8 +35,8 @@ bool InitExtFS() {
     for (u32 i = 1; i < NORM_FS; i++) {
         char fsname[8];
         snprintf(fsname, 7, "%lu:", i);
-        if (f_mount(fs + i, fsname, 1) != FR_OK) return false;
-        fs_mounted[i] = true;
+        if (f_mount(fs + i, fsname, 1) == FR_OK)
+            fs_mounted[i] = true;
     }
     return true;
 }