diff --git a/scripts/build.sh b/scripts/build.sh
index 702586d..09e90d3 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -20,7 +20,7 @@ haiku)
     ;;
 linux)
     default_cc="gcc"
-    CFLAGS="$CFLAGS -D _XOPEN_SOURCE"
+    CFLAGS="$CFLAGS -D _GNU_SOURCE"
     ;;
 netbsd)
     default_cc="gcc"