diff --git a/src/corelib/tools/qregularexpression.cpp b/src/corelib/tools/qregularexpression.cpp
index 259cfaba7e..88ce4caea3 100644
--- a/src/corelib/tools/qregularexpression.cpp
+++ b/src/corelib/tools/qregularexpression.cpp
@@ -1731,7 +1731,7 @@ QRegularExpressionMatchIterator QRegularExpression::globalMatch(const QString &s
 
     \sa QRegularExpression::OptimizeOnFirstUsageOption
 */
-void QRegularExpression::optimize()
+void QRegularExpression::optimize() const
 {
     if (!isValid()) // will compile the pattern
         return;
diff --git a/src/corelib/tools/qregularexpression.h b/src/corelib/tools/qregularexpression.h
index 3352e2b3d5..ce91eace5f 100644
--- a/src/corelib/tools/qregularexpression.h
+++ b/src/corelib/tools/qregularexpression.h
@@ -125,7 +125,7 @@ public:
                                                 MatchType matchType       = NormalMatch,
                                                 MatchOptions matchOptions = NoMatchOption) const;
 
-    void optimize();
+    void optimize() const;
 
     static QString escape(const QString &str);