diff --git a/subprocess.hpp b/subprocess.hpp
index a3d4dd9..ec15a51 100755
--- a/subprocess.hpp
+++ b/subprocess.hpp
@@ -631,7 +631,7 @@ namespace util
     int status = 0;
     int ret = -1;
     while (1) {
-      ret = waitpid(pid, &status, WNOHANG);
+      ret = waitpid(pid, &status, 0);
       if (ret == -1) break;
       if (ret == 0) continue;
       return std::make_pair(ret, status);