diff --git a/dlls/d3d11/d3d11_main.c b/dlls/d3d11/d3d11_main.c
index 4091bcadbd2..b5bf8cdcdef 100644
--- a/dlls/d3d11/d3d11_main.c
+++ b/dlls/d3d11/d3d11_main.c
@@ -28,7 +28,7 @@
 
 WINE_DEFAULT_DEBUG_CHANNEL(d3d11);
 
-const char *debug_d3d_driver_type(D3D_DRIVER_TYPE driver_type)
+static const char *debug_d3d_driver_type(D3D_DRIVER_TYPE driver_type)
 {
     switch(driver_type)
     {