diff --git a/test/lit.cfg b/test/lit.cfg
index d7ace851..c1163755 100644
--- a/test/lit.cfg
+++ b/test/lit.cfg
@@ -63,7 +63,7 @@ class LibcxxTestFormat(lit.formats.FileBasedTest):
                 report += "\n\nExpected compilation to fail!"
                 return lit.Test.FAIL, report
         else:
-            exec_file = tempfile.NamedTemporaryFile(suffix="exe")
+            exec_file = tempfile.NamedTemporaryFile(suffix=".exe")
             exec_path = exec_file.name
             exec_file.close()