diff --git a/gfx/common/win32_common.c b/gfx/common/win32_common.c
index 4093115514..4599df9b6f 100644
--- a/gfx/common/win32_common.c
+++ b/gfx/common/win32_common.c
@@ -286,7 +286,8 @@ void unset_doubleclick_on_titlebar(void)
    doubleclick_on_titlebar = false;
 }
 
-INT_PTR_COMPAT CALLBACK PickCoreProc(HWND hDlg, UINT message,
+static INT_PTR_COMPAT CALLBACK PickCoreProc(
+      HWND hDlg, UINT message,
         WPARAM wParam, LPARAM lParam)
 {
    size_t list_size;