diff --git a/src/m_sched.c b/src/m_sched.c
index 49c6b5261d5ffcb4a82516da163ed3eab312ab09..9ddb2624ec5d2a2677aa74c68a2a3461d2dd444a 100644
--- a/src/m_sched.c
+++ b/src/m_sched.c
@@ -69,8 +69,8 @@ void clock_unset(t_clock *x)
         else
         {
             t_clock *x2 = clock_setlist;
-            while (x2->c_next != x) x2 = x2->c_next;
-            x2->c_next = x->c_next;
+            while (x2 && x2->c_next != x) x2 = x2->c_next;
+            if (x2) x2->c_next = x->c_next;
         }
         x->c_settime = -1;
     }