diff -ruN qwt-6.1.3.orig/textengines/mathml/mathml.pro qwt-6.1.3/textengines/mathml/mathml.pro
--- qwt-6.1.3.orig/textengines/mathml/mathml.pro	2016-06-13 10:14:22.990600268 +0300
+++ qwt-6.1.3/textengines/mathml/mathml.pro	2017-04-20 23:52:55.654701571 +0300
@@ -60,7 +60,8 @@
 
     QMAKE_PKGCONFIG_LIBDIR = $${QWT_INSTALL_LIBS}
     QMAKE_PKGCONFIG_INCDIR = $${QWT_INSTALL_HEADERS}
-
+    QMAKE_PKGCONFIG_DESTDIR = pkgconfig
+    
     # QMAKE_PKGCONFIG_DESTDIR is buggy, in combination
     # with including pri files: better don't use it