diff --git a/dlls/wined3d/surface.c b/dlls/wined3d/surface.c
index f162764db76..ce669e1dea9 100644
--- a/dlls/wined3d/surface.c
+++ b/dlls/wined3d/surface.c
@@ -4131,11 +4131,11 @@ static void flush_to_framebuffer_drawpixels(struct wined3d_surface *surface,
     context_release(context);
 }
 
-HRESULT d3dfmt_get_conv(struct wined3d_surface *surface, BOOL need_alpha_ck,
+HRESULT d3dfmt_get_conv(const struct wined3d_surface *surface, BOOL need_alpha_ck,
         BOOL use_texturing, struct wined3d_format *format, CONVERT_TYPES *convert)
 {
     BOOL colorkey_active = need_alpha_ck && (surface->CKeyFlags & WINEDDSD_CKSRCBLT);
-    struct wined3d_device *device = surface->resource.device;
+    const struct wined3d_device *device = surface->resource.device;
     const struct wined3d_gl_info *gl_info = &device->adapter->gl_info;
     BOOL blit_supported = FALSE;
 
diff --git a/dlls/wined3d/wined3d_private.h b/dlls/wined3d/wined3d_private.h
index a0941b6ee81..374c631a398 100644
--- a/dlls/wined3d/wined3d_private.h
+++ b/dlls/wined3d/wined3d_private.h
@@ -2159,7 +2159,7 @@ typedef enum {
     CONVERT_RGB32_888
 } CONVERT_TYPES;
 
-HRESULT d3dfmt_get_conv(struct wined3d_surface *surface, BOOL need_alpha_ck, BOOL use_texturing,
+HRESULT d3dfmt_get_conv(const struct wined3d_surface *surface, BOOL need_alpha_ck, BOOL use_texturing,
         struct wined3d_format *format, CONVERT_TYPES *convert) DECLSPEC_HIDDEN;
 void d3dfmt_p8_init_palette(struct wined3d_surface *surface, BYTE table[256][4], BOOL colorkey) DECLSPEC_HIDDEN;