diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index 6b09b97..369d931 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -136,6 +136,13 @@
   let s:t_normal = &t_me
 endif
 
+if has('mac')
+  " In MacOS, when starting a shell in a terminal, a bash deprecation warning
+  " message is displayed. This breaks the terminal test. Disable the warning
+  " message.
+  let $BASH_SILENCE_DEPRECATION_WARNING = 1
+endif
+
 " Prepare for calling test_garbagecollect_now().
 let v:testing = 1