diff --git a/dlls/wined3d/surface.c b/dlls/wined3d/surface.c
index f26cffe746..f162764db7 100644
--- a/dlls/wined3d/surface.c
+++ b/dlls/wined3d/surface.c
@@ -288,7 +288,7 @@ static inline void surface_get_rect(struct wined3d_surface *surface, const RECT
 }
 
 /* GL locking and context activation is done by the caller */
-void draw_textured_quad(struct wined3d_surface *src_surface, const RECT *src_rect,
+void draw_textured_quad(const struct wined3d_surface *src_surface, const RECT *src_rect,
         const RECT *dst_rect, WINED3DTEXTUREFILTERTYPE Filter)
 {
     struct blt_info info;
diff --git a/dlls/wined3d/wined3d_private.h b/dlls/wined3d/wined3d_private.h
index a33d94f2a6..a0941b6ee8 100644
--- a/dlls/wined3d/wined3d_private.h
+++ b/dlls/wined3d/wined3d_private.h
@@ -2095,8 +2095,8 @@ void get_drawable_size_swapchain(const struct wined3d_context *context, UINT *wi
 void get_drawable_size_backbuffer(const struct wined3d_context *context, UINT *width, UINT *height) DECLSPEC_HIDDEN;
 void get_drawable_size_fbo(const struct wined3d_context *context, UINT *width, UINT *height) DECLSPEC_HIDDEN;
 
-void draw_textured_quad(struct wined3d_surface *src_surface, const RECT *src_rect,
-                        const RECT *dst_rect, WINED3DTEXTUREFILTERTYPE Filter) DECLSPEC_HIDDEN;
+void draw_textured_quad(const struct wined3d_surface *src_surface, const RECT *src_rect,
+        const RECT *dst_rect, WINED3DTEXTUREFILTERTYPE Filter) DECLSPEC_HIDDEN;
 void flip_surface(struct wined3d_surface *front, struct wined3d_surface *back) DECLSPEC_HIDDEN;
 
 /* Surface flags: */