diff --git a/ppp/Makefile b/ppp/Makefile
index 0ff55c2..3ad91a0 100644
--- a/ppp/Makefile
+++ b/ppp/Makefile
@@ -2,7 +2,7 @@
 
 -include ../makeopts
 
-CFLAGS		+= $(COPTS) -fPIC
+CFLAGS		+= $(COPTS) -fPIC $(DAHDI_INCLUDE)
 LDFLAGS		+= -shared
 
 INCLUDE_DIR	= $(includedir)/pppd