diff --git a/p2p_manager.cc b/p2p_manager.cc
index 127e5ff..1ee124d 100644
--- a/p2p_manager.cc
+++ b/p2p_manager.cc
@@ -16,6 +16,9 @@
 
 // This provides access to timestamps with nanosecond resolution in
 // struct stat, See NOTES in stat(2) for details.
+#ifndef _DEFAULT_SOURCE
+#define _DEFAULT_SOURCE
+#endif
 #ifndef _BSD_SOURCE
 #define _BSD_SOURCE
 #endif