diff --git a/lang/qt/tests/Makefile.am b/lang/qt/tests/Makefile.am
index 4a14e63d..7658a73a 100644
--- a/lang/qt/tests/Makefile.am
+++ b/lang/qt/tests/Makefile.am
@@ -36,7 +36,7 @@ LDADD = ../../cpp/src/libgpgmepp.la ../src/libqgpgme.la \
 
 AM_CPPFLAGS = -I$(top_builddir)/src @GPG_ERROR_CFLAGS@ \
               @GPGME_QT_CFLAGS@ @GPG_ERROR_CFLAGS@ @LIBASSUAN_CFLAGS@ \
-              @GPGME_QTTEST_CFLAGS@ \
+              @GPGME_QTTEST_CFLAGS@ -DBUILDING_QGPGME \
               -I$(top_srcdir)/lang/cpp/src -I$(top_srcdir)/lang/qt/src \
               -DTOP_SRCDIR="$(top_srcdir)"