diff --git a/sim_tape.c b/sim_tape.c
index 9ade108c..312731c3 100644
--- a/sim_tape.c
+++ b/sim_tape.c
@@ -4240,7 +4240,7 @@ static void ansi_fill_text_buffer (FILE *f, char *buf, size_t buf_size, size_t r
             memcpy (buf + offset, tmp, move_size);
             offset += move_size;
             if (offset == buf_size) {
-                fseek (f, start + move_size, SEEK_SET);
+                (void)fseek (f, start + move_size, SEEK_SET);
                 break;
                 }
             }
diff --git a/sim_timer.c b/sim_timer.c
index 49e61d6d..8c773037 100644
--- a/sim_timer.c
+++ b/sim_timer.c
@@ -2530,8 +2530,8 @@ else {
                 }
             crtc->hz = 0;                          /* back to 0 */
             }
+        sim_debug (DBG_CAL|DBG_INT, &sim_timer_dev, "_rtcn_configure_calibrated_clock(newtmr=%d) - Changing Calibrated Timer from %d (%dHz) to %d (%dHz)\n", newtmr, sim_calb_tmr, crtc->last_hz, tmr, rtc->hz);
         }
-    sim_debug (DBG_CAL|DBG_INT, &sim_timer_dev, "_rtcn_configure_calibrated_clock(newtmr=%d) - Changing Calibrated Timer from %d (%dHz) to %d (%dHz)\n", newtmr, sim_calb_tmr, crtc->hz, tmr, crtc->hz);
     sim_calb_tmr = tmr;
     }
 sim_calb_tmr = tmr;
@@ -2767,36 +2767,38 @@ if ((inst_delay == 0) && (usec_delay != 0))
     inst_delay_d = inst_delay = 1;  /* Minimum non-zero delay is 1 instruction */
 if (uptr->usecs_remaining != 0.0)   /* No calibrated timer yet, wait one cycle */
     inst_delay_d = inst_delay = 1;  /* Minimum non-zero delay is 1 instruction */
-crtc = &rtcs[sim_calb_tmr];
-if ((sim_calb_tmr != -1) && (crtc->hz)) {       /* Calibrated Timer available? */
-    int32 inst_til_tick = sim_activate_time (crtc->timer_unit) - 1;
-    int32 ticks_til_calib = crtc->hz - crtc->ticks;
-    double usecs_per_tick = floor (1000000.0 / crtc->hz);
-    int32 inst_til_calib = inst_til_tick + ((ticks_til_calib - 1) * crtc->currd);
-    uint32 usecs_til_calib = (uint32)ceil(inst_til_calib / inst_per_usec);
+if (sim_calb_tmr != -1) {
+    crtc = &rtcs[sim_calb_tmr];
+    if (crtc->hz) {                 /* Calibrated Timer available? */
+        int32 inst_til_tick = sim_activate_time (crtc->timer_unit) - 1;
+        int32 ticks_til_calib = crtc->hz - crtc->ticks;
+        double usecs_per_tick = floor (1000000.0 / crtc->hz);
+        int32 inst_til_calib = inst_til_tick + ((ticks_til_calib - 1) * crtc->currd);
+        uint32 usecs_til_calib = (uint32)ceil(inst_til_calib / inst_per_usec);
 
-    if ((uptr != crtc->timer_unit) &&                       /* Not scheduling calibrated timer */
-        (inst_til_tick > 0)) {                              /* and tick not pending? */
-        if (inst_delay_d > (double)inst_til_calib) {        /* long wait? */
-            stat = sim_clock_coschedule_tmr (uptr, sim_calb_tmr, ticks_til_calib - 1);
-            uptr->usecs_remaining = (stat == SCPE_OK) ? usec_delay - usecs_til_calib : 0.0;
-            sim_debug (DBG_TIM, &sim_timer_dev, "sim_timer_activate_after(%s, %.0f usecs) - coscheduling with with calibrated timer(%d), ticks=%d, usecs_remaining=%.0f usecs, inst_til_tick=%d, ticks_til_calib=%d, usecs_til_calib=%u\n", 
-                       sim_uname(uptr), usec_delay, sim_calb_tmr, ticks_til_calib, uptr->usecs_remaining, inst_til_tick, ticks_til_calib, usecs_til_calib);
-            sim_debug (DBG_CHK, &sim_timer_dev, "sim_timer_activate_after(%s, %.0f usecs) - result = %.0f usecs, %.0f usecs\n", 
-                       sim_uname(uptr), usec_delay, sim_timer_activate_time_usecs (ouptr), sim_timer_activate_time_usecs (uptr));
-            return stat;
-            }
-        if ((usec_delay > (2 * usecs_per_tick)) &&
-            (ticks_til_calib > 1)) {                  /* long wait? */
-            double usecs_til_tick = floor (inst_til_tick / inst_per_usec);
+        if ((uptr != crtc->timer_unit) &&                   /* Not scheduling calibrated timer */
+            (inst_til_tick > 0)) {                          /* and tick not pending? */
+            if (inst_delay_d > (double)inst_til_calib) {    /* long wait? */
+                stat = sim_clock_coschedule_tmr (uptr, sim_calb_tmr, ticks_til_calib - 1);
+                uptr->usecs_remaining = (stat == SCPE_OK) ? usec_delay - usecs_til_calib : 0.0;
+                sim_debug (DBG_TIM, &sim_timer_dev, "sim_timer_activate_after(%s, %.0f usecs) - coscheduling with with calibrated timer(%d), ticks=%d, usecs_remaining=%.0f usecs, inst_til_tick=%d, ticks_til_calib=%d, usecs_til_calib=%u\n", 
+                           sim_uname(uptr), usec_delay, sim_calb_tmr, ticks_til_calib, uptr->usecs_remaining, inst_til_tick, ticks_til_calib, usecs_til_calib);
+                sim_debug (DBG_CHK, &sim_timer_dev, "sim_timer_activate_after(%s, %.0f usecs) - result = %.0f usecs, %.0f usecs\n", 
+                           sim_uname(uptr), usec_delay, sim_timer_activate_time_usecs (ouptr), sim_timer_activate_time_usecs (uptr));
+                return stat;
+                }
+            if ((usec_delay > (2 * usecs_per_tick)) &&
+                (ticks_til_calib > 1)) {                    /* long wait? */
+                double usecs_til_tick = floor (inst_til_tick / inst_per_usec);
 
-            stat = sim_clock_coschedule_tmr (uptr, sim_calb_tmr, 0);
-            uptr->usecs_remaining = (stat == SCPE_OK) ? usec_delay - usecs_til_tick : 0.0;
-            sim_debug (DBG_TIM, &sim_timer_dev, "sim_timer_activate_after(%s, %.0f usecs) - coscheduling with with calibrated timer(%d), ticks=%d, usecs_remaining=%.0f usecs, inst_til_tick=%d, usecs_til_tick=%.0f\n", 
-                       sim_uname(uptr), usec_delay, sim_calb_tmr, 0, uptr->usecs_remaining, inst_til_tick, usecs_til_tick);
-            sim_debug (DBG_CHK, &sim_timer_dev, "sim_timer_activate_after(%s, %.0f usecs) - result = %.0f usecs, %.0f usecs\n", 
-                       sim_uname(uptr), usec_delay, sim_timer_activate_time_usecs (ouptr), sim_timer_activate_time_usecs (uptr));
-            return stat;
+                stat = sim_clock_coschedule_tmr (uptr, sim_calb_tmr, 0);
+                uptr->usecs_remaining = (stat == SCPE_OK) ? usec_delay - usecs_til_tick : 0.0;
+                sim_debug (DBG_TIM, &sim_timer_dev, "sim_timer_activate_after(%s, %.0f usecs) - coscheduling with with calibrated timer(%d), ticks=%d, usecs_remaining=%.0f usecs, inst_til_tick=%d, usecs_til_tick=%.0f\n", 
+                           sim_uname(uptr), usec_delay, sim_calb_tmr, 0, uptr->usecs_remaining, inst_til_tick, usecs_til_tick);
+                sim_debug (DBG_CHK, &sim_timer_dev, "sim_timer_activate_after(%s, %.0f usecs) - result = %.0f usecs, %.0f usecs\n", 
+                           sim_uname(uptr), usec_delay, sim_timer_activate_time_usecs (ouptr), sim_timer_activate_time_usecs (uptr));
+                return stat;
+                }
             }
         }
     }