diff --git a/runtests.py b/runtests.py
@@ -55,7 +55,7 @@ if not (args.program or args.dump_tests or args.debug_normalization):
def md2html(text, prog):
if prog:
- p1 = Popen([prog], stdout=PIPE, stdin=PIPE, stderr=PIPE)
+ p1 = Popen(prog.split(), stdout=PIPE, stdin=PIPE, stderr=PIPE)
[result, err] = p1.communicate(input=text)
return [p1.returncode, result, err]
else: