diff --git a/src/testdir/runtest.vim b/src/testdir/runtest.vim
index 60805f1..3cf2a50 100644
--- a/src/testdir/runtest.vim
+++ b/src/testdir/runtest.vim
@@ -117,6 +117,11 @@
 
 let s:srcdir = expand('%:p:h:h')
 
+if has('win32')
+  " avoid prompt that is long or contains a line break
+  let $PROMPT = '$P$G'
+endif
+
 " Prepare for calling test_garbagecollect_now().
 let v:testing = 1