diff --git a/src/corelib/io/qloggingregistry.cpp b/src/corelib/io/qloggingregistry.cpp
index 7745b8ad945..ee7b7c56132 100644
--- a/src/corelib/io/qloggingregistry.cpp
+++ b/src/corelib/io/qloggingregistry.cpp
@@ -337,11 +337,9 @@ void QLoggingRegistry::registerCategory(QLoggingCategory *cat, QtMsgType enableF
 {
     const auto locker = qt_scoped_lock(registryMutex);
 
-    const auto oldSize = categories.size();
-    auto &e = categories[cat];
-    if (categories.size() != oldSize) {
+    auto r = categories.tryEmplace(cat, enableForLevel);
+    if (r.inserted) {
         // new entry
-        e = enableForLevel;
         (*categoryFilter)(cat);
     }
 }
diff --git a/src/corelib/kernel/qmetatype.cpp b/src/corelib/kernel/qmetatype.cpp
index 045f1e80d4a..f3b9937f6b7 100644
--- a/src/corelib/kernel/qmetatype.cpp
+++ b/src/corelib/kernel/qmetatype.cpp
@@ -1688,12 +1688,8 @@ public:
     bool insertIfNotContains(Key k, const T &f)
     {
         const QWriteLocker locker(&lock);
-        const qsizetype oldSize = map.size();
-        auto &e = map[k];
-        if (map.size() == oldSize) // already present
-            return false;
-        e = f;
-        return true;
+        auto r = map.tryEmplace(k, f);
+        return r.inserted;
     }
 
     const T *function(Key k) const