diff --git a/src/xsettings.c b/src/xsettings.c
index 71cd6a9ad6c..1d6bc712292 100644
--- a/src/xsettings.c
+++ b/src/xsettings.c
@@ -1411,6 +1411,7 @@ If this variable is nil, Emacs ignores system font changes.  */);
 #endif
 
   current_tool_bar_style = Qnil;
+  staticpro (&current_tool_bar_style);
   DEFSYM (Qtool_bar_style, "tool-bar-style");
   defsubr (&Stool_bar_get_system_style);