diff --git a/src/fmacros.h b/src/fmacros.h
index 94d8f6885..f3ae85bcb 100644
--- a/src/fmacros.h
+++ b/src/fmacros.h
@@ -19,7 +19,7 @@
 #define _ALL_SOURCE
 #endif
 
-#if defined(__linux__) || defined(__OpenBSD__)
+#if defined(__linux__) || defined(__OpenBSD__) || defined(__GLIBC__)
 #define _XOPEN_SOURCE 700
 /*
  * On NetBSD, _XOPEN_SOURCE undefines _NETBSD_SOURCE and