diff -up ytnef-1.9.2/lib/libytnef.pc.in.orig ytnef-1.9.2/lib/libytnef.pc.in
--- ytnef-1.9.2/lib/libytnef.pc.in.orig	2017-03-28 10:50:58.496400854 +0200
+++ ytnef-1.9.2/lib/libytnef.pc.in	2017-03-28 10:51:20.576558722 +0200
@@ -8,4 +8,4 @@ Description: Yerase's TNEF Stream Reader
 URL: https://github.com/Yeraze/ytnef
 Version: @VERSION@
 Libs: -L${libdir} -lytnef
-Cflags: -I${includedir}
+Cflags: -I${includedir}/libytnef