diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index a710c6ecba0..a99292f5e03 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -2421,12 +2421,17 @@ static inline qsizetype findCharHelper(QByteArrayView haystack, qsizetype from,
 qsizetype QtPrivate::findByteArray(QByteArrayView haystack, qsizetype from, QByteArrayView needle) noexcept
 {
     const auto ol = needle.size();
-    if (ol == 0)
-        return from;
+    const auto l = haystack.size();
+    if (ol == 0) {
+        if (from < 0)
+            return qMax(from + l, 0);
+        else
+            return from > l ? -1 : from;
+    }
+
     if (ol == 1)
         return findCharHelper(haystack, from, needle.front());
 
-    const auto l = haystack.size();
     if (from > l || ol + from > l)
         return -1;
 
@@ -2461,7 +2466,7 @@ qsizetype QtPrivate::findByteArray(QByteArrayView haystack, qsizetype from, QByt
 
 qsizetype QByteArray::indexOf(char ch, qsizetype from) const
 {
-    return static_cast<int>(findCharHelper(*this, from, ch));
+    return qToByteArrayViewIgnoringNull(*this).indexOf(ch, from);
 }
 
 static qsizetype lastIndexOfHelper(const char *haystack, qsizetype l, const char *needle,
@@ -2556,7 +2561,7 @@ qsizetype QtPrivate::lastIndexOf(QByteArrayView haystack, qsizetype from, QByteA
 
 qsizetype QByteArray::lastIndexOf(char ch, qsizetype from) const
 {
-    return static_cast<int>(lastIndexOfCharHelper(*this, from, ch));
+    return qToByteArrayViewIgnoringNull(*this).lastIndexOf(ch, from);
 }
 
 static inline qsizetype countCharHelper(QByteArrayView haystack, char needle) noexcept
diff --git a/tests/auto/corelib/text/qbytearrayapisymmetry/tst_qbytearrayapisymmetry.cpp b/tests/auto/corelib/text/qbytearrayapisymmetry/tst_qbytearrayapisymmetry.cpp
index 8b517274179..40d7291e41f 100644
--- a/tests/auto/corelib/text/qbytearrayapisymmetry/tst_qbytearrayapisymmetry.cpp
+++ b/tests/auto/corelib/text/qbytearrayapisymmetry/tst_qbytearrayapisymmetry.cpp
@@ -316,12 +316,20 @@ void tst_QByteArrayApiSymmetry::indexOf_data()
     static const char n19[] = { 0x00, 0x00, 0x01, 0x00 };
     QTest::newRow("19") << QByteArray(h19, sizeof(h19)) << QByteArray(n19, sizeof(n19)) << 0 << -1;
 
-    QTest::newRow("empty") << QByteArray("") << QByteArray("x") << 0 << -1;
-    QTest::newRow("null") << QByteArray() << QByteArray("x") << 0 << -1;
+    QTest::newRow("empty from 0") << QByteArray("") << QByteArray("x") << 0 << -1;
+    QTest::newRow("empty from -1") << QByteArray("") << QByteArray("x") << -1 << -1;
+    QTest::newRow("empty from 1") << QByteArray("") << QByteArray("x") << 1 << -1;
+    QTest::newRow("null from 0") << QByteArray() << QByteArray("x") << 0 << -1;
+    QTest::newRow("null from -1") << QByteArray() << QByteArray("x") << -1 << -1;
+    QTest::newRow("null from 1") << QByteArray() << QByteArray("x") << 1 << -1;
     QTest::newRow("null-in-null") << QByteArray() << QByteArray() << 0 << 0;
     QTest::newRow("empty-in-null") << QByteArray() << QByteArray("") << 0 << 0;
     QTest::newRow("null-in-empty") << QByteArray("") << QByteArray() << 0 << 0;
     QTest::newRow("empty-in-empty") << QByteArray("") << QByteArray("") << 0 << 0;
+    QTest::newRow("empty in abc from 0") << abc << QByteArray() << 0 << 0;
+    QTest::newRow("empty in abc from 2") << abc << QByteArray() << 2 << 2;
+    QTest::newRow("empty in abc from 5") << abc << QByteArray() << 5 << -1;
+    QTest::newRow("empty in abc from -1") << abc << QByteArray() << -1 << 2;
 
     QByteArray veryBigHaystack(500, 'a');
     veryBigHaystack += 'B';
@@ -404,12 +412,23 @@ void tst_QByteArrayApiSymmetry::lastIndexOf_data()
     static const char n25[] = { 0x00, 0x00, 0x01, 0x00 };
     QTest::newRow("25") << QByteArray(h25, sizeof(h25)) << QByteArray(n25, sizeof(n25)) << 0 << -1;
 
-    QTest::newRow("empty") << QByteArray("") << QByteArray("x") << -1 << -1;
-    QTest::newRow("null") << QByteArray() << QByteArray("x") << -1 << -1;
+    QTest::newRow("empty from 0") << QByteArray("") << QByteArray("x") << 0 << -1;
+    QTest::newRow("empty from -1") << QByteArray("") << QByteArray("x") << -1 << -1;
+    QTest::newRow("empty from 1") << QByteArray("") << QByteArray("x") << 1 << -1;
+    QTest::newRow("null from 0") << QByteArray() << QByteArray("x") << 0 << -1;
+    QTest::newRow("null from -1") << QByteArray() << QByteArray("x") << -1 << -1;
+    QTest::newRow("null from 1") << QByteArray() << QByteArray("x") << 1 << -1;
     QTest::newRow("null-in-null") << QByteArray() << QByteArray() << -1 << 0;
     QTest::newRow("empty-in-null") << QByteArray() << QByteArray("") << -1 << 0;
     QTest::newRow("null-in-empty") << QByteArray("") << QByteArray() << -1 << 0;
     QTest::newRow("empty-in-empty") << QByteArray("") << QByteArray("") << -1 << 0;
+    QTest::newRow("empty in abc from 0") << abc << QByteArray() << 0 << 0;
+    QTest::newRow("empty in abc from 2") << abc << QByteArray() << 2 << 2;
+    QTest::newRow("empty in abc from 5")
+            << abc << QByteArray() << 5 << -1; // perversely enough, should be 3?
+    QTest::newRow("empty in abc from -1") << abc << QByteArray() << -1 << 3;
+    QTest::newRow("empty in abc from -5")
+            << abc << QByteArray() << -5 << 3; // perversely enough, should be -1?
 }
 
 template<typename Haystack, typename Needle>