-DEFS = $(subs -DHAVE_CONFIG_H,,@DEFS@)
-CPPFLAGS = $(INCLUDEFLAGS) -I. -I$(PRJDIR) -I$(SLIB)
-CFLAGS = -Wall @CFLAGS@
+DEFS += $(subs -DHAVE_CONFIG_H,,@DEFS@)
+CPPFLAGS += $(INCLUDEFLAGS) -I. -I$(PRJDIR) -I$(SLIB)
+CFLAGS += -Wall @CFLAGS@
+LDFLAGS += @LDFLAGS@