diff --git a/src/Makefile b/src/Makefile
index 4880dfe..f3605b6 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -3,8 +3,8 @@ PREFIX	= /usr/local
 DESTDIR	= 
 LIBDIR	= $(PREFIX)/lib
 CC	= cc
-CPPFLAGSF=
-CPPFLAGS= -I ../include
+CPPFLAGSF= -I $(PREFIX)/include -I ../include
+CPPFLAGS=
 CFLAGSF	= -W
 CFLAGS	= -Wall -g -O2 -pedantic
 AR	= ar -rc
diff --git a/src/project.conf b/src/project.conf
index 7900ce4..da20aaa 100644
--- a/src/project.conf
+++ b/src/project.conf
@@ -1,5 +1,5 @@
 targets=libcpp,cpp
-cppflags=-I ../include
+cppflags_force=-I $(PREFIX)/include -I ../include
 cflags_force=-W
 cflags=-Wall -g -O2 -pedantic
 dist=Makefile,common.h,parser.h