diff --git a/src/cdrom/cdrom.c b/src/cdrom/cdrom.c
index 37615a32e..b89232a46 100644
--- a/src/cdrom/cdrom.c
+++ b/src/cdrom/cdrom.c
@@ -1031,8 +1031,8 @@ cdrom_readsector_raw(cdrom_t *dev, uint8_t *buffer, int sector, int ismsf, int c
     memset(raw_buffer, 0, 2448);
     memset(extra_buffer, 0, 296);
 
-    if (!(cdrom_sector_flags & 0xf0)) {		/* 0x00 and 0x08 are illegal modes */
-	cdrom_log("CD-ROM %i: [Mode 1] 0x00 and 0x08 are illegal modes\n", dev->id);
+    if ((cdrom_sector_flags & 0xf8) == 0x08) {		/* 0x08 is an illegal mode */
+	cdrom_log("CD-ROM %i: [Mode 1] 0x08 is an illegal mode\n", dev->id);
 	return 0;
     }
 
diff --git a/src/scsi/scsi_cdrom.c b/src/scsi/scsi_cdrom.c
index a53af6435..e099efe07 100644
--- a/src/scsi/scsi_cdrom.c
+++ b/src/scsi/scsi_cdrom.c
@@ -1626,8 +1626,14 @@ scsi_cdrom_command(scsi_common_t *sc, uint8_t *cdb)
 
 				msf = 1;
 
+				if ((cdb[9] & 0xf8) == 0x08) {
+					/* 0x08 is an illegal mode */
+					scsi_cdrom_invalid_field(dev);
+					break;
+				}
+
 				/* If all the flag bits are cleared, then treat it as a non-data command. */
-				if (cdb[9] == 0x00)
+				if ((cdb[9] == 0x00) && ((cdb[10] & 0x07) == 0x00))
 					dev->sector_len = 0;
 				break;
 			case GPCMD_READ_CD_OLD:
@@ -1638,8 +1644,14 @@ scsi_cdrom_command(scsi_common_t *sc, uint8_t *cdb)
 
 				msf = 0;
 
+				if ((cdb[9] & 0xf8) == 0x08) {
+					/* 0x08 is an illegal mode */
+					scsi_cdrom_invalid_field(dev);
+					break;
+				}
+
 				/* If all the flag bits are cleared, then treat it as a non-data command. */
-				if (cdb[9] == 0x00)
+				if ((cdb[9] == 0x00) && ((cdb[10] & 0x07) == 0x00))
 					dev->sector_len = 0;
 				break;
 		}