diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index 89abbcbff3..3e4d95188d 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -10157,6 +10157,8 @@ char16_t valueTypeToUtf16<char>(char t)
 
 static inline qsizetype qFindChar(QStringView str, QChar ch, qsizetype from, Qt::CaseSensitivity cs) noexcept
 {
+    if (-from > str.size())
+        return -1;
     if (from < 0)
         from = qMax(from + str.size(), qsizetype(0));
     if (from < str.size()) {
diff --git a/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp b/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp
index 48855592dc..32c2576b86 100644
--- a/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp
+++ b/tests/auto/corelib/text/qstringapisymmetry/tst_qstringapisymmetry.cpp
@@ -2268,6 +2268,9 @@ void tst_QStringApiSymmetry::indexOf_data(bool rhsHasVariableLength)
                                      << a << QLatin1String("a") << zeroPos << minus1Pos << minus1Pos;
     QTest::addRow("haystack: null, needle: a") << null << QLatin1String()
                                      << a << QLatin1String("a") << zeroPos << minus1Pos << minus1Pos;
+    QTest::addRow("haystack: anything, needle: a, large negative offset")
+            << "anything" << QLatin1String("anything") << a << QLatin1String("a") << qsizetype(-500)
+            << minus1Pos << minus1Pos;
 
 #define ROW(h, n, st, cs, cis) \
     QTest::addRow("haystack: %s, needle: %s", #h, #n) << h << QLatin1String(#h) \
diff --git a/tests/auto/corelib/tools/collections/tst_collections.cpp b/tests/auto/corelib/tools/collections/tst_collections.cpp
index 34a352c614..5b26ae5faa 100644
--- a/tests/auto/corelib/tools/collections/tst_collections.cpp
+++ b/tests/auto/corelib/tools/collections/tst_collections.cpp
@@ -1710,7 +1710,7 @@ void tst_Collections::qstring()
     QVERIFY (hello.contains('e') != false);
 
     QVERIFY(hello.indexOf('e') == 1);
-    QVERIFY(hello.indexOf('e', -10) == 1);
+    QVERIFY(hello.indexOf('e', -10) == -1);
     QVERIFY(hello.indexOf('l') == 2);
     QVERIFY(hello.indexOf('l',2) == 2);
     QVERIFY(hello.indexOf('l',3) == 3);