diff --git a/src/blur.cpp b/src/blur.cpp
index 8771028e9..fd99265ad 100644
--- a/src/blur.cpp
+++ b/src/blur.cpp
@@ -839,13 +839,13 @@ void BlurEffect::blur(BlurRenderData &renderInfo, const RenderTarget &renderTarg
 
     if (!staticBlurTexture
         && (renderInfo.framebuffers.size() != (m_iterationCount + 1)
-            || renderInfo.textures[0]->size() != backgroundRect.size()
+            || renderInfo.textures[0]->size() != deviceBackgroundRect.size()
             || renderInfo.textures[0]->internalFormat() != textureFormat)) {
         renderInfo.framebuffers.clear();
         renderInfo.textures.clear();
 
         for (size_t i = 0; i <= m_iterationCount; ++i) {
-            auto texture = GLTexture::allocate(textureFormat, backgroundRect.size() / (1 << i));
+            auto texture = GLTexture::allocate(textureFormat, deviceBackgroundRect.size() / (1 << i));
             if (!texture) {
                 qCWarning(KWIN_BLUR) << "Failed to allocate an offscreen texture";
                 return;
@@ -866,8 +866,9 @@ void BlurEffect::blur(BlurRenderData &renderInfo, const RenderTarget &renderTarg
     // Fetch the pixels behind the shape that is going to be blurred.
     if (!staticBlurTexture) {
         const QRegion dirtyRegion = region & backgroundRect;
-        for (const QRect &dirtyRect: dirtyRegion) {
-            renderInfo.framebuffers[0]->blitFromRenderTarget(renderTarget, viewport, dirtyRect, dirtyRect.translated(-backgroundRect.topLeft()));
+        for (const QRect &dirtyRect : dirtyRegion) {
+            const auto destination = snapToPixelGrid(scaledRect(dirtyRect, viewport.scale())).translated(-deviceBackgroundRect.topLeft());
+            renderInfo.framebuffers[0]->blitFromRenderTarget(renderTarget, viewport, dirtyRect, destination);
         }
     }
 
@@ -885,17 +886,17 @@ void BlurEffect::blur(BlurRenderData &renderInfo, const RenderTarget &renderTarg
 
         // The geometry that will be blurred offscreen, in logical pixels.
         {
-            const QRectF localRect = QRectF(0, 0, backgroundRect.width(), backgroundRect.height());
+            const QRectF localRect = QRectF(0, 0, deviceBackgroundRect.width(), deviceBackgroundRect.height());
 
             const float x0 = localRect.left();
             const float y0 = localRect.top();
             const float x1 = localRect.right();
             const float y1 = localRect.bottom();
 
-            const float u0 = x0 / backgroundRect.width();
-            const float v0 = 1.0f - y0 / backgroundRect.height();
-            const float u1 = x1 / backgroundRect.width();
-            const float v1 = 1.0f - y1 / backgroundRect.height();
+            const float u0 = x0 / deviceBackgroundRect.width();
+            const float v0 = 1.0f - y0 / deviceBackgroundRect.height();
+            const float u1 = x1 / deviceBackgroundRect.width();
+            const float v1 = 1.0f - y1 / deviceBackgroundRect.height();
 
             // first triangle
             map[vboIndex++] = GLVertex2D{
@@ -1012,7 +1013,7 @@ void BlurEffect::blur(BlurRenderData &renderInfo, const RenderTarget &renderTarg
             ShaderManager::instance()->pushShader(m_downsamplePass.shader.get());
 
             QMatrix4x4 projectionMatrix;
-            projectionMatrix.ortho(QRectF(0.0, 0.0, backgroundRect.width(), backgroundRect.height()));
+            projectionMatrix.ortho(QRectF(0.0, 0.0, deviceBackgroundRect.width(), deviceBackgroundRect.height()));
 
             m_downsamplePass.shader->setUniform(m_downsamplePass.mvpMatrixLocation, projectionMatrix);
             m_downsamplePass.shader->setUniform(m_downsamplePass.offsetLocation, float(m_offset));
@@ -1044,7 +1045,7 @@ void BlurEffect::blur(BlurRenderData &renderInfo, const RenderTarget &renderTarg
         ShaderManager::instance()->pushShader(m_upsamplePass.shader.get());
 
         QMatrix4x4 projectionMatrix;
-        projectionMatrix.ortho(QRectF(0.0, 0.0, backgroundRect.width(), backgroundRect.height()));
+        projectionMatrix.ortho(QRectF(0.0, 0.0, deviceBackgroundRect.width(), deviceBackgroundRect.height()));
 
         m_upsamplePass.shader->setUniform(m_upsamplePass.topCornerRadiusLocation, static_cast<float>(0));
         m_upsamplePass.shader->setUniform(m_upsamplePass.bottomCornerRadiusLocation, static_cast<float>(0));
@@ -1087,7 +1088,7 @@ void BlurEffect::blur(BlurRenderData &renderInfo, const RenderTarget &renderTarg
         m_upsamplePass.shader->setUniform(m_upsamplePass.topCornerRadiusLocation, topCornerRadius);
         m_upsamplePass.shader->setUniform(m_upsamplePass.bottomCornerRadiusLocation, bottomCornerRadius);
         m_upsamplePass.shader->setUniform(m_upsamplePass.antialiasingLocation, m_settings.roundedCorners.antialiasing);
-        m_upsamplePass.shader->setUniform(m_upsamplePass.blurSizeLocation, QVector2D(backgroundRect.width(), backgroundRect.height()));
+        m_upsamplePass.shader->setUniform(m_upsamplePass.blurSizeLocation, QVector2D(deviceBackgroundRect.width(), deviceBackgroundRect.height()));
         m_upsamplePass.shader->setUniform(m_upsamplePass.opacityLocation, static_cast<float>(opacity));
 
         projectionMatrix = viewport.projectionMatrix();