patch 7.4.1860
Problem:    Using a partial for timer_start() may cause a crash.
Solution:   Set the copyID in timer objects. (Ozaki Kiichi)
diff --git a/src/eval.c b/src/eval.c
index 3578c99..d30a766 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -7046,6 +7046,10 @@
     abort = abort || set_ref_in_nb_channel(copyID);
 #endif
 
+#ifdef FEAT_TIMERS
+    abort = abort || set_ref_in_timer(copyID);
+#endif
+
     if (!abort)
     {
 	/*
diff --git a/src/ex_cmds2.c b/src/ex_cmds2.c
index a90fe7d..9adaea3 100644
--- a/src/ex_cmds2.c
+++ b/src/ex_cmds2.c
@@ -1252,6 +1252,25 @@
     remove_timer(timer);
     free_timer(timer);
 }
+
+/*
+ * Mark references in partials of timers.
+ */
+    int
+set_ref_in_timer(int copyID)
+{
+    int		abort = FALSE;
+    timer_T	*timer;
+    typval_T	tv;
+
+    for (timer = first_timer; timer != NULL; timer = timer->tr_next)
+    {
+	tv.v_type = VAR_PARTIAL;
+	tv.vval.v_partial = timer->tr_partial;
+	abort = abort || set_ref_in_item(&tv, copyID, NULL, NULL);
+    }
+    return abort;
+}
 # endif
 
 #if defined(FEAT_SYN_HL) && defined(FEAT_RELTIME) && defined(FEAT_FLOAT)
diff --git a/src/proto/ex_cmds2.pro b/src/proto/ex_cmds2.pro
index 5e5b4d4..8d9b72a 100644
--- a/src/proto/ex_cmds2.pro
+++ b/src/proto/ex_cmds2.pro
@@ -22,6 +22,7 @@
 long check_due_timer(void);
 timer_T *find_timer(int id);
 void stop_timer(timer_T *timer);
+int set_ref_in_timer(int copyID);
 void profile_divide(proftime_T *tm, int count, proftime_T *tm2);
 void profile_add(proftime_T *tm, proftime_T *tm2);
 void profile_self(proftime_T *self, proftime_T *total, proftime_T *children);
diff --git a/src/testdir/test_timers.vim b/src/testdir/test_timers.vim
index 7ef51e5..0969377 100644
--- a/src/testdir/test_timers.vim
+++ b/src/testdir/test_timers.vim
@@ -8,6 +8,10 @@
   let s:val += 1
 endfunc
 
+func MyHandlerWithLists(lists, timer)
+  let x = string(a:lists)
+endfunc
+
 func Test_oneshot()
   let s:val = 0
   let timer = timer_start(50, 'MyHandler')
@@ -42,4 +46,10 @@
   sleep 200m
   call assert_equal(1, s:val)
 endfunc
+
+func Test_retain_partial()
+  call timer_start(100, function('MyHandlerWithLists', [['a']]))
+  call test_garbagecollect_now()
+  sleep 200m
+endfunc
 " vim: ts=2 sw=0 et
diff --git a/src/version.c b/src/version.c
index eb9f2c7..515f518 100644
--- a/src/version.c
+++ b/src/version.c
@@ -754,6 +754,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1860,
+/**/
     1859,
 /**/
     1858,