diff --git a/config/default.conf b/config/default.conf
index ff863ec..8bdb54c 100644
--- a/config/default.conf
+++ b/config/default.conf
@@ -118,9 +118,9 @@ INCDIR	 =	$(abspath $(PRTDIR))/include
 # default gmake variable in implicit rules
 # ------------------------------------
 
-CFLAGS 	  = 	$(OPTIM) $(MACHDEF) -I$(INCDIR)
+CFLAGS 	  := $(CFLAGS)	$(OPTIM) $(MACHDEF) -I$(INCDIR)
 
-LDFLAGS	  =     -L$(LIBDIR) -L.
+LDFLAGS	  := $(LDFLAGS)    -L$(LIBDIR) -L.
 
 LDLIBS	  =	    $(LIBS) $(MALLOC_LIBS) $(MATH_LIBS) $(CC_LIBS)