diff --git a/dlls/wined3d/resource.c b/dlls/wined3d/resource.c
index 95c9b7ff197..a3dadec3ab1 100644
--- a/dlls/wined3d/resource.c
+++ b/dlls/wined3d/resource.c
@@ -478,7 +478,7 @@ void wined3d_resource_update_draw_binding(struct wined3d_resource *resource)
     }
 }
 
-const struct wined3d_format *wined3d_resource_get_decompress_format(struct wined3d_resource *resource)
+const struct wined3d_format *wined3d_resource_get_decompress_format(const struct wined3d_resource *resource)
 {
     const struct wined3d_adapter *adapter = resource->device->adapter;
     if (resource->format_flags & (WINED3DFMT_FLAG_SRGB_READ | WINED3DFMT_FLAG_SRGB_WRITE)
diff --git a/dlls/wined3d/wined3d_private.h b/dlls/wined3d/wined3d_private.h
index 19341a59b75..b96d3a53c09 100644
--- a/dlls/wined3d/wined3d_private.h
+++ b/dlls/wined3d/wined3d_private.h
@@ -3125,7 +3125,7 @@ void resource_unload(struct wined3d_resource *resource) DECLSPEC_HIDDEN;
 BOOL wined3d_resource_allocate_sysmem(struct wined3d_resource *resource) DECLSPEC_HIDDEN;
 void wined3d_resource_free_sysmem(struct wined3d_resource *resource) DECLSPEC_HIDDEN;
 const struct wined3d_format *wined3d_resource_get_decompress_format(
-        struct wined3d_resource *resource) DECLSPEC_HIDDEN;
+        const struct wined3d_resource *resource) DECLSPEC_HIDDEN;
 GLbitfield wined3d_resource_gl_map_flags(DWORD d3d_flags) DECLSPEC_HIDDEN;
 GLenum wined3d_resource_gl_legacy_map_flags(DWORD d3d_flags) DECLSPEC_HIDDEN;
 BOOL wined3d_resource_is_offscreen(struct wined3d_resource *resource) DECLSPEC_HIDDEN;