diff --git a/dlls/wined3d/device.c b/dlls/wined3d/device.c
index 6e8eb2da099..ec9126f5108 100644
--- a/dlls/wined3d/device.c
+++ b/dlls/wined3d/device.c
@@ -4553,7 +4553,7 @@ HRESULT CDECL wined3d_device_set_software_vertex_processing(struct wined3d_devic
     return WINED3D_OK;
 }
 
-BOOL CDECL wined3d_device_get_software_vertex_processing(struct wined3d_device *device)
+BOOL CDECL wined3d_device_get_software_vertex_processing(const struct wined3d_device *device)
 {
     static BOOL warned;
 
diff --git a/include/wine/wined3d.h b/include/wine/wined3d.h
index 3dec8ba4c8d..c6949bd1cb4 100644
--- a/include/wine/wined3d.h
+++ b/include/wine/wined3d.h
@@ -2243,7 +2243,7 @@ HRESULT __cdecl wined3d_device_get_render_target(struct wined3d_device *device,
 HRESULT __cdecl wined3d_device_get_sampler_state(const struct wined3d_device *device,
         UINT sampler_idx, WINED3DSAMPLERSTATETYPE state, DWORD *value);
 HRESULT __cdecl wined3d_device_get_scissor_rect(const struct wined3d_device *device, RECT *rect);
-BOOL __cdecl wined3d_device_get_software_vertex_processing(struct wined3d_device *device);
+BOOL __cdecl wined3d_device_get_software_vertex_processing(const struct wined3d_device *device);
 HRESULT __cdecl wined3d_device_get_stream_source(const struct wined3d_device *device,
         UINT stream_idx, struct wined3d_buffer **buffer, UINT *offset, UINT *stride);
 HRESULT __cdecl wined3d_device_get_stream_source_freq(const struct wined3d_device *device,