diff --git a/screws.scad b/screws.scad
index 83b33e1..e0438fd 100644
--- a/screws.scad
+++ b/screws.scad
@@ -12,7 +12,7 @@
 // FileSummary: ISO (metric) and UTS screws and nuts.
 //////////////////////////////////////////////////////////////////////
 
-BOSL2_SCREWS = is_undef(_BOSL2_STD) && (is_undef(BOSL2_NO_STD_WARNING) || !BOSL2_NO_STD_WARNING) ?
+_BOSL2_SCREWS = is_undef(_BOSL2_STD) && (is_undef(BOSL2_NO_STD_WARNING) || !BOSL2_NO_STD_WARNING) ?
        echo("Warning: screws.scad included without std.scad; dependencies may be missing\nSet BOSL2_NO_STD_WARNING = true to mute this warning.") true : true;