diff -up libassuan-2.5.3/src/libassuan.pc.in.includedir libassuan-2.5.3/src/libassuan.pc.in
--- libassuan-2.5.3/src/libassuan.pc.in.includedir	2018-10-25 11:20:28.000000000 +0200
+++ libassuan-2.5.3/src/libassuan.pc.in	2019-08-19 10:29:10.536279378 +0200
@@ -9,6 +9,6 @@ Name: libassuan
 Description: IPC library for the GnuPG components
 Requires: gpg-error
 Version: @PACKAGE_VERSION@
-Cflags: @LIBASSUAN_CONFIG_CFLAGS@
+Cflags: @LIBASSUAN_CONFIG_CFLAGS@ -I${includedir}
 Libs: @LIBASSUAN_CONFIG_LIBS@
 URL: https://www.gnupg.org/related_software/libassuan/index.html