diff --git a/src/plugins/qt4projectmanager/qt4projectconfigwidget.cpp b/src/plugins/qt4projectmanager/qt4projectconfigwidget.cpp
index ca78da73b9a..2140e8f6006 100644
--- a/src/plugins/qt4projectmanager/qt4projectconfigwidget.cpp
+++ b/src/plugins/qt4projectmanager/qt4projectconfigwidget.cpp
@@ -255,12 +255,12 @@ void Qt4ProjectConfigWidget::updateProblemLabel()
     } else if (targetMismatch) {
         setProblemLabel(shadowBuildWarning + tr("A build for a different project exists in %1, which will be overwritten.",
                                                 "%1 build directory")
-                        .arg(m_buildConfiguration->buildDirectory()));
+                        .arg(QDir::toNativeSeparators(m_buildConfiguration->buildDirectory())));
         return;
     } else if (incompatibleBuild) {
         setProblemLabel(shadowBuildWarning +tr("An incompatible build exists in %1, which will be overwritten.",
                                                "%1 build directory")
-                        .arg(m_buildConfiguration->buildDirectory()));
+                        .arg(QDir::toNativeSeparators(m_buildConfiguration->buildDirectory())));
         return;
     } else if (!shadowBuildWarning.isEmpty()) {
         setProblemLabel(shadowBuildWarning);