diff --git a/src/corelib/time/qtimezoneprivate_win.cpp b/src/corelib/time/qtimezoneprivate_win.cpp
index b1abcb7a970..82666407d2c 100644
--- a/src/corelib/time/qtimezoneprivate_win.cpp
+++ b/src/corelib/time/qtimezoneprivate_win.cpp
@@ -186,22 +186,24 @@ bool isSameRule(const QWinTimeZonePrivate::QWinTransitionRule &last,
 
 QList<QByteArray> availableWindowsIds()
 {
-    // TODO Consider caching results in a global static, very unlikely to change.
-    QList<QByteArray> list;
-    QWinRegistryKey key(HKEY_LOCAL_MACHINE, tzRegPath);
-    if (key.isValid()) {
-        DWORD idCount = 0;
-        if (RegQueryInfoKey(key, 0, 0, 0, &idCount, 0, 0, 0, 0, 0, 0, 0) == ERROR_SUCCESS
-            && idCount > 0) {
-            for (DWORD i = 0; i < idCount; ++i) {
-                DWORD maxLen = MAX_KEY_LENGTH;
-                TCHAR buffer[MAX_KEY_LENGTH];
-                if (RegEnumKeyEx(key, i, buffer, &maxLen, 0, 0, 0, 0) == ERROR_SUCCESS)
-                    list.append(QString::fromWCharArray(buffer).toUtf8());
+    static const QList<QByteArray> cache = [] {
+        QList<QByteArray> list;
+        QWinRegistryKey key(HKEY_LOCAL_MACHINE, tzRegPath);
+        if (key.isValid()) {
+            DWORD idCount = 0;
+            if (RegQueryInfoKey(key, 0, 0, 0, &idCount, 0, 0, 0, 0, 0, 0, 0) == ERROR_SUCCESS
+                && idCount > 0) {
+                for (DWORD i = 0; i < idCount; ++i) {
+                    DWORD maxLen = MAX_KEY_LENGTH;
+                    TCHAR buffer[MAX_KEY_LENGTH];
+                    if (RegEnumKeyEx(key, i, buffer, &maxLen, 0, 0, 0, 0) == ERROR_SUCCESS)
+                        list.append(QString::fromWCharArray(buffer).toUtf8());
+                }
             }
         }
-    }
-    return list;
+        return list;
+    }();
+    return cache;
 }
 
 QByteArray windowsSystemZoneId()