diff --git a/scp.c b/scp.c
index 53da17f2..055629e1 100644
--- a/scp.c
+++ b/scp.c
@@ -5791,17 +5791,28 @@ return (dptr ? (dptr->lname? dptr->lname: dptr->name) : "");
 
 const char *sim_uname (UNIT *uptr)
 {
-DEVICE *d = find_dev_from_unit(uptr);
-static AIO_TLS char uname[CBUFSIZE];
+DEVICE *d;
+char uname[CBUFSIZE];
 
+if (uptr->uname)
+    return uptr->uname;
+d = find_dev_from_unit(uptr);
 if (!d)
     return "";
 if (d->numunits == 1)
-    return sim_dname (d);
-sprintf (uname, "%s%d", sim_dname (d), (int)(uptr-d->units));
-return uname;
+    sprintf (uname, "%s", sim_dname (d));
+else
+    sprintf (uname, "%s%d", sim_dname (d), (int)(uptr-d->units));
+return sim_set_uname (uptr, uname);
 }
 
+const char *sim_set_uname (UNIT *uptr, const char *uname)
+{
+free (uptr->uname);
+uptr->uname = strcpy ((char *)malloc (1 + strlen (uname)), uname);
+}
+
+
 /* Save command
 
    sa[ve] filename              save state to specified file
diff --git a/scp.h b/scp.h
index 29ed7d2a..858db320 100644
--- a/scp.h
+++ b/scp.h
@@ -144,6 +144,7 @@ t_stat reset_all (uint32 start_device);
 t_stat reset_all_p (uint32 start_device);
 const char *sim_dname (DEVICE *dptr);
 const char *sim_uname (UNIT *dptr);
+const char *sim_set_uname (UNIT *uptr, const char *uname);
 t_stat get_yn (const char *ques, t_stat deflt);
 int sim_isspace (char c);
 int sim_islower (char c);
diff --git a/sim_defs.h b/sim_defs.h
index 2ad7a71f..ac3c85f0 100644
--- a/sim_defs.h
+++ b/sim_defs.h
@@ -547,6 +547,7 @@ struct UNIT {
     void                *tmxr;                          /* TMXR linkage */
     t_bool              (*cancel)(UNIT *);
     double              usecs_remaining;                /* time balance for long delays */
+    char                *uname;                         /* Unit name */
 #ifdef SIM_ASYNCH_IO
     void                (*a_check_completion)(UNIT *);
     t_bool              (*a_is_active)(UNIT *);