diff --git a/src/libs/utils/mimetypes2/mimedatabase.cpp b/src/libs/utils/mimetypes2/mimedatabase.cpp
index 2f4d36d39d5..4433e3d1819 100644
--- a/src/libs/utils/mimetypes2/mimedatabase.cpp
+++ b/src/libs/utils/mimetypes2/mimedatabase.cpp
@@ -43,7 +43,7 @@ namespace Utils {
 template <typename T>
 class DuplicateTracker {
 public:
-    bool hasSeen(const T &v) { return Utils::insert(seen, v); }
+    bool hasSeen(const T &v) { return !Utils::insert(seen, v); }
 private:
     QSet<T> seen;
 };