diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index c14f44e..0d53121 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -606,6 +606,8 @@
   " A test can set g:test_is_flaky to retry running the test.
   let g:test_is_flaky = 0
 
+  let g:check_screendump_called = v:false
+
   " A test can set g:max_run_nr to change the max retry count.
   let g:max_run_nr = 5
   if has('mac')