diff --git a/PDP11/pdp11_rq.c b/PDP11/pdp11_rq.c
index f5df3fca..2aa513f0 100644
--- a/PDP11/pdp11_rq.c
+++ b/PDP11/pdp11_rq.c
@@ -172,7 +172,7 @@ extern int32 MMR2;
 #define unit_plug       u4                              /* drive unit plug value */
 #define io_status       u5                              /* io status from callback */
 #define io_complete     u6                              /* io completion flag */
-#define rqxb            filebuf                         /* xfer buffer */
+#define rqxb            up11                            /* xfer buffer */
 #define RQ_RMV(u)       ((drv_tab[GET_DTYPE (u->flags)].flgs & RQDF_RMV)? \
                         UF_RMV: 0)
 #define RQ_WPH(u)       (((drv_tab[GET_DTYPE (u->flags)].flgs & RQDF_RO) || \
diff --git a/sim_defs.h b/sim_defs.h
index 18f390a4..ba63d092 100644
--- a/sim_defs.h
+++ b/sim_defs.h
@@ -602,6 +602,7 @@ struct UNIT {
     void                *up8;                           /* device specific */
     uint16              us9;                            /* device specific */
     uint16              us10;                           /* device specific */
+    void                *up11;                          /* device specific */
     DRVTYP              *drvtyp;                        /* Drive Type */
     void                *tmxr;                          /* TMXR linkage */
     uint32              recsize;                        /* Tape specific info */