diff --git a/src/testdir/test_channel.vim b/src/testdir/test_channel.vim
index d3f36f8..15ca9dd 100644
--- a/src/testdir/test_channel.vim
+++ b/src/testdir/test_channel.vim
@@ -1945,10 +1945,11 @@
   endif
 
   func OutCb(chan, msg)
+    let g:val += 1
   endfunc
 
   func ExitCb(job, status)
-    let g:val = 1
+    let g:val += 1
     call Resume()
   endfunc
 
@@ -1967,6 +1968,10 @@
   call timer_start(1, 'TimerCb')
   let elapsed = Standby(&ut)
   call assert_inrange(1, &ut / 2, elapsed)
+
+  " Wait for both OutCb() and ExitCb() to have been called before deleting
+  " them.
+  call WaitForAssert({-> assert_equal(2, g:val)})
   call job_stop(g:job)
 
   delfunc OutCb