diff --git a/sys/fs/cd9660/cd9660_mount.h b/sys/fs/cd9660/cd9660_mount.h
index 5263912d529..8cc6a8655fa 100644
--- a/sys/fs/cd9660/cd9660_mount.h
+++ b/sys/fs/cd9660/cd9660_mount.h
@@ -52,3 +52,4 @@ struct iso_args {
 #define	ISOFSMNT_GENS	0x00000002	/* enable generation numbers */
 #define	ISOFSMNT_EXTATT	0x00000004	/* enable extended attributes */
 #define ISOFSMNT_NOJOLIET 0x00000008	/* disable Joliet Ext.*/
+#define ISOFSMNT_BROKENJOLIET 0x00000010/* allow broken Joliet disks */
diff --git a/sys/fs/cd9660/cd9660_vfsops.c b/sys/fs/cd9660/cd9660_vfsops.c
index 606f9d37941..e73fb7efdc5 100644
--- a/sys/fs/cd9660/cd9660_vfsops.c
+++ b/sys/fs/cd9660/cd9660_vfsops.c
@@ -355,7 +355,8 @@ iso_mountfs(devvp, mp, p, argp)
 					if (bcmp(sup->escape, "%/E", 3) == 0)
 						joliet_level = 3;
 
-					if (isonum_711 (sup->flags) & 1)
+					if ((isonum_711 (sup->flags) & 1) &&
+					    (argp->flags & ISOFSMNT_BROKENJOLIET) == 0)
 						joliet_level = 0;
 				}
 			}
diff --git a/sys/isofs/cd9660/cd9660_mount.h b/sys/isofs/cd9660/cd9660_mount.h
index 5263912d529..8cc6a8655fa 100644
--- a/sys/isofs/cd9660/cd9660_mount.h
+++ b/sys/isofs/cd9660/cd9660_mount.h
@@ -52,3 +52,4 @@ struct iso_args {
 #define	ISOFSMNT_GENS	0x00000002	/* enable generation numbers */
 #define	ISOFSMNT_EXTATT	0x00000004	/* enable extended attributes */
 #define ISOFSMNT_NOJOLIET 0x00000008	/* disable Joliet Ext.*/
+#define ISOFSMNT_BROKENJOLIET 0x00000010/* allow broken Joliet disks */
diff --git a/sys/isofs/cd9660/cd9660_vfsops.c b/sys/isofs/cd9660/cd9660_vfsops.c
index 606f9d37941..e73fb7efdc5 100644
--- a/sys/isofs/cd9660/cd9660_vfsops.c
+++ b/sys/isofs/cd9660/cd9660_vfsops.c
@@ -355,7 +355,8 @@ iso_mountfs(devvp, mp, p, argp)
 					if (bcmp(sup->escape, "%/E", 3) == 0)
 						joliet_level = 3;
 
-					if (isonum_711 (sup->flags) & 1)
+					if ((isonum_711 (sup->flags) & 1) &&
+					    (argp->flags & ISOFSMNT_BROKENJOLIET) == 0)
 						joliet_level = 0;
 				}
 			}