diff --git a/spa/include/spa/utils/string.h b/spa/include/spa/utils/string.h
index 060ef7d62..775daa3ae 100644
--- a/spa/include/spa/utils/string.h
+++ b/spa/include/spa/utils/string.h
@@ -9,6 +9,7 @@
 extern "C" {
 #endif
 
+#define _XOPEN_SOURCE 700
 #include <stdarg.h>
 #include <stdbool.h>
 #include <errno.h>