diff --git a/src/corelib/tools/qregularexpression.cpp b/src/corelib/tools/qregularexpression.cpp
index 316681e6522..2cd76b389d2 100644
--- a/src/corelib/tools/qregularexpression.cpp
+++ b/src/corelib/tools/qregularexpression.cpp
@@ -1137,11 +1137,11 @@ void QRegularExpressionPrivate::optimizePattern(OptimizePatternOption option)
 {
     Q_ASSERT(compiledPattern);
 
-    QMutexLocker lock(&mutex);
-
     if (studyData.load()) // already optimized
         return;
 
+    QMutexLocker lock(&mutex);
+
     if ((option == LazyOptimizeOption) && (++usedCount != qt_qregularexpression_optimize_after_use_count))
         return;