diff --git a/dlls/d3d11/device.c b/dlls/d3d11/device.c
index 8fc6cb1ba60..38845ec198a 100644
--- a/dlls/d3d11/device.c
+++ b/dlls/d3d11/device.c
@@ -3186,17 +3186,21 @@ static void STDMETHODCALLTYPE d3d10_device_CopySubresourceRegion(ID3D10Device1 *
             iface, dst_resource, dst_subresource_idx, dst_x, dst_y, dst_z,
             src_resource, src_subresource_idx, src_box);
 
+    if (src_box)
+    {
+        wined3d_src_box.left = src_box->left;
+        wined3d_src_box.top = src_box->top;
+        wined3d_src_box.front = src_box->front;
+        wined3d_src_box.right = src_box->right;
+        wined3d_src_box.bottom = src_box->bottom;
+        wined3d_src_box.back = src_box->back;
+    }
+
     wined3d_dst_resource = wined3d_resource_from_d3d10_resource(dst_resource);
     wined3d_src_resource = wined3d_resource_from_d3d10_resource(src_resource);
-    wined3d_src_box.left = src_box->left;
-    wined3d_src_box.top = src_box->top;
-    wined3d_src_box.front = src_box->front;
-    wined3d_src_box.right = src_box->right;
-    wined3d_src_box.bottom = src_box->bottom;
-    wined3d_src_box.back = src_box->back;
     wined3d_mutex_lock();
     wined3d_device_copy_sub_resource_region(device->wined3d_device, wined3d_dst_resource, dst_subresource_idx,
-            dst_x, dst_y, dst_z, wined3d_src_resource, src_subresource_idx, &wined3d_src_box);
+            dst_x, dst_y, dst_z, wined3d_src_resource, src_subresource_idx, src_box ? &wined3d_src_box : NULL);
     wined3d_mutex_unlock();
 }
 
diff --git a/dlls/wined3d/device.c b/dlls/wined3d/device.c
index d3080833010..87221c38e82 100644
--- a/dlls/wined3d/device.c
+++ b/dlls/wined3d/device.c
@@ -4002,15 +4002,25 @@ HRESULT CDECL wined3d_device_copy_sub_resource_region(struct wined3d_device *dev
     }
     src_surface = surface_from_resource(tmp);
 
+    if (src_box)
+    {
+        src_rect.left = src_box->left;
+        src_rect.top = src_box->top;
+        src_rect.right = src_box->right;
+        src_rect.bottom = src_box->bottom;
+    }
+    else
+    {
+        src_rect.left = 0;
+        src_rect.top = 0;
+        src_rect.right = src_surface->resource.width;
+        src_rect.bottom = src_surface->resource.height;
+    }
+
     dst_rect.left = dst_x;
     dst_rect.top = dst_y;
-    dst_rect.right = dst_x + (src_box->right - src_box->left);
-    dst_rect.bottom = dst_y + (src_box->bottom - src_box->top);
-
-    src_rect.left = src_box->left;
-    src_rect.top = src_box->top;
-    src_rect.right = src_box->right;
-    src_rect.bottom = src_box->bottom;
+    dst_rect.right = dst_x + (src_rect.right - src_rect.left);
+    dst_rect.bottom = dst_y + (src_rect.bottom - src_rect.top);
 
     if (FAILED(hr = wined3d_surface_blt(dst_surface, &dst_rect, src_surface, &src_rect, 0, NULL, WINED3D_TEXF_POINT)))
         ERR("Failed to blit, hr %#x.\n", hr);