diff --git a/include/lo2s/pipe.hpp b/include/lo2s/pipe.hpp
index fbde33ae..9b017ee7 100644
--- a/include/lo2s/pipe.hpp
+++ b/include/lo2s/pipe.hpp
@@ -59,7 +59,7 @@ class Pipe
     void fd_flags(std::size_t fd, int flags);
     void close_fd(std::size_t fd);
 
-    int fds_[2];
-    bool fd_open_[2];
+    int fds_[2] = { -1, -1 };
+    bool fd_open_[2] = { false, false };
 };
 } // namespace lo2s