diff --git a/src/plugins/qmakeprojectmanager/qmakeprojectimporter.cpp b/src/plugins/qmakeprojectmanager/qmakeprojectimporter.cpp
index e159f5dd6dc..832fb1a6809 100644
--- a/src/plugins/qmakeprojectmanager/qmakeprojectimporter.cpp
+++ b/src/plugins/qmakeprojectmanager/qmakeprojectimporter.cpp
@@ -27,9 +27,9 @@
 #include <utils/qtcassert.h>
 
 #include <QDir>
-#include <QFileInfo>
-#include <QStringList>
 #include <QLoggingCategory>
+#include <QSet>
+#include <QStringList>
 
 #include <memory>
 
@@ -63,11 +63,14 @@ FilePaths QmakeProjectImporter::importCandidates()
 {
     FilePaths candidates{projectFilePath().absolutePath()};
 
+    QSet<FilePath> seenBaseDirs;
     for (Kit *k : KitManager::kits()) {
         const FilePath sbdir = QmakeBuildConfiguration::shadowBuildDirectory
                     (projectFilePath(), k, QString(), BuildConfiguration::Unknown);
 
         const FilePath baseDir = sbdir.absolutePath();
+        if (!Utils::insert(seenBaseDirs, baseDir))
+            continue;
         for (const FilePath &path : baseDir.dirEntries(QDir::Dirs | QDir::NoDotAndDotDot)) {
             if (!candidates.contains(path))
                 candidates << path;