--- a/lang/cpp/tests/Makefile.am	2019-04-07 21:58:14.917535900 -0400
+++ b/lang/cpp/tests/Makefile.am	2019-04-07 21:58:23.229581500 -0400
@@ -24,7 +24,7 @@
         ../../../src/libgpgme.la @GPG_ERROR_LIBS@ \
         @LDADD_FOR_TESTS_KLUDGE@ -lstdc++
 
-AM_CPPFLAGS = -I$(top_srcdir)/lang/cpp/src -I$(top_builddir)/src \
+AM_CPPFLAGS = -I$(top_srcdir)/lang/cpp/src -I$(top_builddir)/lang/cpp/src -I$(top_builddir)/src \
               @GPG_ERROR_CFLAGS@ @GPG_ERROR_CFLAGS@ \
               @LIBASSUAN_CFLAGS@ -DBUILDING_GPGMEPP \
               -DTOP_SRCDIR="$(top_srcdir)"