diff --git a/cont.c b/cont.c
index 082b47dae2..1f82a7944e 100644
--- a/cont.c
+++ b/cont.c
@@ -262,7 +262,17 @@ static inline void
 ec_switch(rb_thread_t *th, rb_fiber_t *fib)
 {
     rb_execution_context_t *ec = &fib->cont.saved_ec;
+
     ruby_current_execution_context_ptr = th->ec = ec;
+
+    /*
+     * timer-thread may set trap interrupt on previous th->ec at any time;
+     * ensure we do not delay (or lose) the trap interrupt handling.
+     */
+    if (th->vm->main_thread == th && rb_signal_buff_size() > 0) {
+        RUBY_VM_SET_TRAP_INTERRUPT(ec);
+    }
+
     VM_ASSERT(ec->fiber_ptr->cont.self == 0 || ec->vm_stack != NULL);
 }