diff --git a/src/corelib/text/qbytearray.cpp b/src/corelib/text/qbytearray.cpp
index 293b8f72fe..27986baeae 100644
--- a/src/corelib/text/qbytearray.cpp
+++ b/src/corelib/text/qbytearray.cpp
@@ -1962,7 +1962,7 @@ QByteArray &QByteArray::insert(qsizetype i, const char *str, qsizetype len)
     // ### optimize me
     if (d->needsDetach() || newSize > capacity() || shouldGrow) {
         auto flags = d->detachFlags() | Data::GrowsForward;
-        if (i <= newSize / 4)  // using QList's policy
+        if (i <= oldSize / 4)  // using QList's policy
             flags |= Data::GrowsBackwards;
         reallocGrowData(newSize + 1, flags);
     }
@@ -2010,7 +2010,7 @@ QByteArray &QByteArray::insert(qsizetype i, qsizetype count, char ch)
     // ### optimize me
     if (d->needsDetach() || newSize > capacity() || shouldGrow) {
         auto flags = d->detachFlags() | Data::GrowsForward;
-        if (i <= newSize / 4)  // using QList's policy
+        if (i <= oldSize / 4)  // using QList's policy
             flags |= Data::GrowsBackwards;
         reallocGrowData(newSize + 1, flags);
     }
diff --git a/src/corelib/text/qstring.cpp b/src/corelib/text/qstring.cpp
index bf37f2e675..b7344353ec 100644
--- a/src/corelib/text/qstring.cpp
+++ b/src/corelib/text/qstring.cpp
@@ -2690,7 +2690,7 @@ QString& QString::insert(qsizetype i, const QChar *unicode, qsizetype size)
     const bool shouldGrow = d->shouldGrowBeforeInsert(d.begin() + qMin(i, oldSize), size);
 
     auto flags = d->detachFlags() | Data::GrowsForward;
-    if (i <= newSize / 4)
+    if (i <= oldSize / 4)
         flags |= Data::GrowsBackwards;
 
     // ### optimize me
@@ -2724,7 +2724,7 @@ QString& QString::insert(qsizetype i, QChar ch)
     const bool shouldGrow = d->shouldGrowBeforeInsert(d.begin() + qMin(i, oldSize), 1);
 
     auto flags = d->detachFlags() | Data::GrowsForward;
-    if (i <= newSize / 4)
+    if (i <= oldSize / 4)
         flags |= Data::GrowsBackwards;
 
     // ### optimize me
diff --git a/src/corelib/tools/qlist.h b/src/corelib/tools/qlist.h
index e94c108f0c..a704de54ea 100644
--- a/src/corelib/tools/qlist.h
+++ b/src/corelib/tools/qlist.h
@@ -616,7 +616,7 @@ QList<T>::insert(qsizetype i, qsizetype n, parameter_type t)
     const bool shouldGrow = d->shouldGrowBeforeInsert(d.begin() + i, n);
     if (d->needsDetach() || newSize > d->allocatedCapacity() || shouldGrow) {
         typename Data::ArrayOptions flags = d->detachFlags() | Data::GrowsForward;
-        if (size_t(i) <= newSize / 4)
+        if (i <= d.size / 4)
             flags |= Data::GrowsBackwards;
 
         DataPointer detached(DataPointer::allocateGrow(d, newSize, flags));
@@ -648,7 +648,7 @@ QList<T>::emplace(qsizetype i, Args&&... args)
     const size_t newSize = size() + 1;
     if (d->needsDetach() || newSize > d->allocatedCapacity() || shouldGrow) {
         typename Data::ArrayOptions flags = d->detachFlags() | Data::GrowsForward;
-        if (size_t(i) <= newSize / 4)
+        if (i <= d.size / 4)
             flags |= Data::GrowsBackwards;
 
         DataPointer detached(DataPointer::allocateGrow(d, newSize, flags));