diff --git a/src/corelib/tools/qarraydatapointer.h b/src/corelib/tools/qarraydatapointer.h
index 4eb90ac35e..65ebc296d4 100644
--- a/src/corelib/tools/qarraydatapointer.h
+++ b/src/corelib/tools/qarraydatapointer.h
@@ -130,19 +130,22 @@ public:
         return d;
     }
 
+    bool needsDetach() const
+    {
+        return (!d->isMutable() || d->ref.isShared());
+    }
+
     void setSharable(bool sharable)
     {
-        // Can't call setSharable on static read-only data, like shared_null
-        // and the internal shared-empties.
-        if (d->alloc == 0 && d->size == 0) {
-            d = Data::allocate(0, sharable
-                    ? QArrayData::Default
-                    : QArrayData::Unsharable);
-            return;
+        if (needsDetach()) {
+            Data *detached = clone(sharable
+                    ? d->detachFlags() & ~QArrayData::Unsharable
+                    : d->detachFlags() | QArrayData::Unsharable);
+            QArrayDataPointer old(d);
+            d = detached;
+        } else {
+            d->ref.setSharable(sharable);
         }
-
-        detach();
-        d->ref.setSharable(sharable);
     }
 
     void swap(QArrayDataPointer &other)
@@ -158,7 +161,7 @@ public:
 
     bool detach()
     {
-        if (!d->isMutable() || d->ref.isShared()) {
+        if (needsDetach()) {
             Data *copy = clone(d->detachFlags());
             QArrayDataPointer old(d);
             d = copy;
diff --git a/tests/auto/corelib/tools/qarraydata/simplevector.h b/tests/auto/corelib/tools/qarraydata/simplevector.h
index 641516e0d0..7e679704c8 100644
--- a/tests/auto/corelib/tools/qarraydata/simplevector.h
+++ b/tests/auto/corelib/tools/qarraydata/simplevector.h
@@ -175,7 +175,7 @@ public:
         if (size() == newSize)
             return;
 
-        if (d->ref.isShared() || newSize > capacity()) {
+        if (d.needsDetach() || newSize > capacity()) {
             SimpleVector detached(Data::allocate(
                         d->detachCapacity(newSize), d->detachFlags()));
             if (newSize) {
@@ -211,7 +211,7 @@ public:
             return;
 
         T *const begin = d->begin();
-        if (d->ref.isShared()
+        if (d.needsDetach()
                 || capacity() - size() < size_t(last - first)) {
             SimpleVector detached(Data::allocate(
                         d->detachCapacity(size() + (last - first)),
@@ -232,7 +232,7 @@ public:
         if (first == last)
             return;
 
-        if (d->ref.isShared()
+        if (d.needsDetach()
                 || capacity() - size() < size_t(last - first)) {
             SimpleVector detached(Data::allocate(
                         d->detachCapacity(size() + (last - first)),
@@ -272,7 +272,7 @@ public:
         T *const begin = d->begin();
         T *const where = begin + position;
         const T *const end = begin + d->size;
-        if (d->ref.isShared()
+        if (d.needsDetach()
                 || capacity() - size() < size_t(last - first)) {
             SimpleVector detached(Data::allocate(
                         d->detachCapacity(size() + (last - first)),