--- a/ripperX.pc.in
+++ b/ripperX.pc.in
@@ -1,6 +1,7 @@
 prefix=@prefix@
 exec_prefix=@exec_prefix@
 libdir=@libdir@
+includedir=@includedir@
 
 pkglibdir=${libdir}/@PACKAGE@
 pkgincludedir=${includedir}/@PACKAGE@