diff --git a/config/qt.m4 b/config/qt.m4
index 8c1a818b33..2cd4263f06 100644
--- a/config/qt.m4
+++ b/config/qt.m4
@@ -424,6 +424,7 @@ qtHaveModule(core5compat):	QT += core5compat
 percent.target = %
 percent.commands = @echo -n "\$(\$(@))\ "
 QMAKE_EXTRA_TARGETS += percent
+QMAKE_PROJECT_DEPTH = 0
 EOF1
 	    $QT_QMAKE $lyx_test_qt_pro -o $lyx_test_qt_mak 1>/dev/null 2>&1
 	    QT_CORE_INCLUDES=`cd $lyx_test_qt_dir; make -s -f $lyx_test_qt_mak INCPATH | sed 's/-I\. //g'`
@@ -452,6 +453,7 @@ qtHaveModule(widgets):		QT += widgets
 percent.target = %
 percent.commands = @echo -n "\$(\$(@))\ "
 QMAKE_EXTRA_TARGETS += percent
+QMAKE_PROJECT_DEPTH = 0
 EOF2
 		$QT_QMAKE $lyx_test_qt_pro -o $lyx_test_qt_mak 1>/dev/null 2>&1
 		QT_INCLUDES=`cd $lyx_test_qt_dir; make -s -f $lyx_test_qt_mak INCPATH | sed 's/-I\. //g'`