diff --git a/lib/makefile.dj b/lib/makefile.dj
index 067459d59..8ab2d575d 100644
--- a/lib/makefile.dj
+++ b/lib/makefile.dj
@@ -26,12 +26,14 @@
 #
 
 DEPEND_PREREQ = curl_config.h
-VPATH  = vtls
+VPATH  = vtls vauth
 TOPDIR = ..
 
 include ../packages/DOS/common.dj
 include Makefile.inc
 
+CFLAGS += -DBUILDING_LIBCURL
+
 SOURCES = $(sort $(CSOURCES))
 OBJECTS = $(addprefix $(OBJ_DIR)/, $(notdir $(SOURCES:.c=.o)))