diff --git a/src/gui/rhi/qrhid3d11.cpp b/src/gui/rhi/qrhid3d11.cpp
index e924966585..2dc5763bd9 100644
--- a/src/gui/rhi/qrhid3d11.cpp
+++ b/src/gui/rhi/qrhid3d11.cpp
@@ -1418,7 +1418,7 @@ void QRhiD3D11::enqueueResourceUpdates(QRhiCommandBuffer *cb, QRhiResourceUpdate
         if (u.type == QRhiResourceUpdateBatchPrivate::BufferOp::DynamicUpdate) {
             QD3D11Buffer *bufD = QRHI_RES(QD3D11Buffer, u.buf);
             Q_ASSERT(bufD->m_type == QRhiBuffer::Dynamic);
-            memcpy(bufD->dynBuf.data() + u.offset, u.data.constData(), size_t(u.dataSize));
+            memcpy(bufD->dynBuf + u.offset, u.data.constData(), size_t(u.dataSize));
             bufD->hasPendingDynamicUpdates = true;
         } else if (u.type == QRhiResourceUpdateBatchPrivate::BufferOp::StaticUpload) {
             QD3D11Buffer *bufD = QRHI_RES(QD3D11Buffer, u.buf);
@@ -1445,7 +1445,7 @@ void QRhiD3D11::enqueueResourceUpdates(QRhiCommandBuffer *cb, QRhiResourceUpdate
             QD3D11Buffer *bufD = QRHI_RES(QD3D11Buffer, u.buf);
             if (bufD->m_type == QRhiBuffer::Dynamic) {
                 u.result->data.resize(u.readSize);
-                memcpy(u.result->data.data(), bufD->dynBuf.constData() + u.offset, size_t(u.readSize));
+                memcpy(u.result->data.data(), bufD->dynBuf + u.offset, size_t(u.readSize));
             } else {
                 BufferReadback readback;
                 readback.result = u.result;
@@ -2155,7 +2155,7 @@ void QRhiD3D11::updateShaderResourceBindings(QD3D11ShaderResourceBindings *srbD,
 
 void QRhiD3D11::executeBufferHostWrites(QD3D11Buffer *bufD)
 {
-    if (!bufD->hasPendingDynamicUpdates)
+    if (!bufD->hasPendingDynamicUpdates || bufD->m_size < 1)
         return;
 
     Q_ASSERT(bufD->m_type == QRhiBuffer::Dynamic);
@@ -2163,7 +2163,7 @@ void QRhiD3D11::executeBufferHostWrites(QD3D11Buffer *bufD)
     D3D11_MAPPED_SUBRESOURCE mp;
     HRESULT hr = context->Map(bufD->buffer, 0, D3D11_MAP_WRITE_DISCARD, 0, &mp);
     if (SUCCEEDED(hr)) {
-        memcpy(mp.pData, bufD->dynBuf.constData(), size_t(bufD->dynBuf.size()));
+        memcpy(mp.pData, bufD->dynBuf, size_t(bufD->m_size));
         context->Unmap(bufD->buffer, 0);
     } else {
         qWarning("Failed to map buffer: %s", qPrintable(comErrorMessage(hr)));
@@ -2600,11 +2600,12 @@ void QD3D11Buffer::destroy()
     if (!buffer)
         return;
 
-    dynBuf.clear();
-
     buffer->Release();
     buffer = nullptr;
 
+    delete[] dynBuf;
+    dynBuf = nullptr;
+
     if (uav) {
         uav->Release();
         uav = nullptr;
@@ -2664,7 +2665,7 @@ bool QD3D11Buffer::create()
     }
 
     if (m_type == Dynamic) {
-        dynBuf.resize(m_size);
+        dynBuf = new char[nonZeroSize];
         hasPendingDynamicUpdates = false;
     }
 
diff --git a/src/gui/rhi/qrhid3d11_p_p.h b/src/gui/rhi/qrhid3d11_p_p.h
index a4d5098084..e033c5b0b7 100644
--- a/src/gui/rhi/qrhid3d11_p_p.h
+++ b/src/gui/rhi/qrhid3d11_p_p.h
@@ -69,7 +69,7 @@ struct QD3D11Buffer : public QRhiBuffer
     ID3D11UnorderedAccessView *unorderedAccessView();
 
     ID3D11Buffer *buffer = nullptr;
-    QByteArray dynBuf;
+    char *dynBuf = nullptr;
     bool hasPendingDynamicUpdates = false;
     ID3D11UnorderedAccessView *uav = nullptr;
     uint generation = 0;
diff --git a/src/gui/rhi/qrhigles2.cpp b/src/gui/rhi/qrhigles2.cpp
index 6f140487d6..e787d439c2 100644
--- a/src/gui/rhi/qrhigles2.cpp
+++ b/src/gui/rhi/qrhigles2.cpp
@@ -1697,7 +1697,7 @@ void QRhiGles2::enqueueResourceUpdates(QRhiCommandBuffer *cb, QRhiResourceUpdate
             QGles2Buffer *bufD = QRHI_RES(QGles2Buffer, u.buf);
             Q_ASSERT(bufD->m_type == QRhiBuffer::Dynamic);
             if (bufD->m_usage.testFlag(QRhiBuffer::UniformBuffer)) {
-                memcpy(bufD->ubuf.data() + u.offset, u.data.constData(), size_t(u.dataSize));
+                memcpy(bufD->ubuf + u.offset, u.data.constData(), size_t(u.dataSize));
             } else {
                 trackedBufferBarrier(cbD, bufD, QGles2Buffer::AccessUpdate);
                 QGles2CommandBuffer::Command cmd;
@@ -1714,7 +1714,7 @@ void QRhiGles2::enqueueResourceUpdates(QRhiCommandBuffer *cb, QRhiResourceUpdate
             Q_ASSERT(bufD->m_type != QRhiBuffer::Dynamic);
             Q_ASSERT(u.offset + u.dataSize <= bufD->m_size);
             if (bufD->m_usage.testFlag(QRhiBuffer::UniformBuffer)) {
-                memcpy(bufD->ubuf.data() + u.offset, u.data.constData(), size_t(u.dataSize));
+                memcpy(bufD->ubuf + u.offset, u.data.constData(), size_t(u.dataSize));
             } else {
                 trackedBufferBarrier(cbD, bufD, QGles2Buffer::AccessUpdate);
                 QGles2CommandBuffer::Command cmd;
@@ -1730,7 +1730,7 @@ void QRhiGles2::enqueueResourceUpdates(QRhiCommandBuffer *cb, QRhiResourceUpdate
             QGles2Buffer *bufD = QRHI_RES(QGles2Buffer, u.buf);
             if (bufD->m_usage.testFlag(QRhiBuffer::UniformBuffer)) {
                 u.result->data.resize(u.readSize);
-                memcpy(u.result->data.data(), bufD->ubuf.constData() + u.offset, size_t(u.readSize));
+                memcpy(u.result->data.data(), bufD->ubuf + u.offset, size_t(u.readSize));
                 if (u.result->completed)
                     u.result->completed();
             } else {
@@ -2836,7 +2836,7 @@ void QRhiGles2::bindShaderResources(QRhiGraphicsPipeline *maybeGraphicsPs, QRhiC
                 }
             }
             QGles2Buffer *bufD = QRHI_RES(QGles2Buffer, b->u.ubuf.buf);
-            const QByteArray bufView = QByteArray::fromRawData(bufD->ubuf.constData() + viewOffset,
+            const QByteArray bufView = QByteArray::fromRawData(bufD->ubuf + viewOffset,
                                                                b->u.ubuf.maybeSize ? b->u.ubuf.maybeSize : bufD->m_size);
             QGles2UniformDescriptionVector &uniforms(maybeGraphicsPs ? QRHI_RES(QGles2GraphicsPipeline, maybeGraphicsPs)->uniforms
                                                      : QRHI_RES(QGles2ComputePipeline, maybeComputePs)->uniforms);
@@ -3706,6 +3706,8 @@ void QGles2Buffer::destroy()
     e.buffer.buffer = buffer;
 
     buffer = 0;
+    delete[] ubuf;
+    ubuf = nullptr;
 
     QRHI_RES_RHI(QRhiGles2);
     rhiD->releaseQueue.append(e);
@@ -3729,7 +3731,7 @@ bool QGles2Buffer::create()
             qWarning("Uniform buffer: multiple usages specified, this is not supported by the OpenGL backend");
             return false;
         }
-        ubuf.resize(nonZeroSize);
+        ubuf = new char[nonZeroSize];
         QRHI_PROF_F(newBuffer(this, uint(nonZeroSize), 0, 1));
         return true;
     }
diff --git a/src/gui/rhi/qrhigles2_p_p.h b/src/gui/rhi/qrhigles2_p_p.h
index bee9b3249e..c004b7f171 100644
--- a/src/gui/rhi/qrhigles2_p_p.h
+++ b/src/gui/rhi/qrhigles2_p_p.h
@@ -68,7 +68,7 @@ struct QGles2Buffer : public QRhiBuffer
 
     GLuint buffer = 0;
     GLenum targetForDataOps;
-    QByteArray ubuf;
+    char *ubuf = nullptr;
     enum Access {
         AccessNone,
         AccessVertex,