diff --git a/libs/re/Makefile b/libs/re/Makefile
index c3cc27bef..fbafd4713 100644
--- a/libs/re/Makefile
+++ b/libs/re/Makefile
@@ -28,6 +28,10 @@ endef
 
 TARGET_CFLAGS += $(FPIC)
 
+ifneq ($(CONFIG_USE_EGLIBC),)
+TARGET_CFLAGS += -D_GNU_SOURCE
+endif
+
 define Build/Compile
 	$(MAKE) -C $(PKG_BUILD_DIR) \
 		HAVE_LIBRESOLV= \