diff --git a/src/light.c b/src/light.c
index aea499de1..555995eec 100644
--- a/src/light.c
+++ b/src/light.c
@@ -148,6 +148,7 @@ delete_ls(light_source *ls)
     }
     if (curr) {
         assert(curr == ls);
+        (void) memset((genericptr_t) ls, 0, sizeof(light_source));
         free((genericptr_t) ls);
         gv.vision_full_recalc = 1;
     } else {
@@ -433,6 +434,7 @@ save_light_sources(NHFILE *nhfp, int range)
             /* if global and not doing local, or vice versa, remove it */
             if (is_global ^ (range == RANGE_LEVEL)) {
                 *prev = curr->next;
+                (void) memset((genericptr_t) curr, 0, sizeof(light_source));
                 free((genericptr_t) curr);
             } else {
                 prev = &(*prev)->next;
diff --git a/src/timeout.c b/src/timeout.c
index e5ae39531..fc853e795 100644
--- a/src/timeout.c
+++ b/src/timeout.c
@@ -2162,6 +2162,7 @@ run_timers(void)
         if (curr->kind == TIMER_OBJECT)
             (curr->arg.a_obj)->timed--;
         (*timeout_funcs[curr->func_index].f)(&curr->arg, curr->timeout);
+        (void) memset((genericptr_t) curr, 0, sizeof(timer_element));
         free((genericptr_t) curr);
     }
 }
@@ -2236,6 +2237,7 @@ stop_timer(short func_index, anything *arg)
             (arg->a_obj)->timed--;
         if ((cleanup_func = timeout_funcs[doomed->func_index].cleanup) != 0)
             (*cleanup_func)(arg, timeout);
+        (void) memset((genericptr_t) doomed, 0, sizeof(timer_element));
         free((genericptr_t) doomed);
         return (timeout - gm.moves);
     }
@@ -2313,6 +2315,7 @@ obj_stop_timers(struct obj *obj)
                 gt.timer_base = curr->next;
             if ((cleanup_func = timeout_funcs[curr->func_index].cleanup) != 0)
                 (*cleanup_func)(&curr->arg, curr->timeout);
+            (void) memset((genericptr_t) curr, 0, sizeof(timer_element));
             free((genericptr_t) curr);
         } else {
             prev = curr;
@@ -2353,6 +2356,7 @@ spot_stop_timers(coordxy x, coordxy y, short func_index)
                 gt.timer_base = curr->next;
             if ((cleanup_func = timeout_funcs[curr->func_index].cleanup) != 0)
                 (*cleanup_func)(&curr->arg, curr->timeout);
+            (void) memset((genericptr_t) curr, 0, sizeof(timer_element));
             free((genericptr_t) curr);
         } else {
             prev = curr;
@@ -2618,6 +2622,7 @@ save_timers(NHFILE *nhfp, int range)
                     prev->next = curr->next;
                 else
                     gt.timer_base = curr->next;
+                (void) memset((genericptr_t) curr, 0, sizeof(timer_element));
                 free((genericptr_t) curr);
                 /* prev stays the same */
             } else {