diff --git a/makedef.pl b/makedef.pl
index 6edab18a1da6..c39830eaf406 100644
--- a/makedef.pl
+++ b/makedef.pl
@@ -109,7 +109,9 @@ BEGIN
 while (<CFG>) {
     $define{$1} = 1 if /^\s*\#\s*define\s+(MYMALLOC|MULTIPLICITY
                                            |KILL_BY_SIGPRC
-                                           |(?:PERL|USE|HAS)_\w+)\b/x;
+                                           |(?:PERL|USE|HAS|LC_ALL)_\w+)\b/x;
+                                           # XXX need to add PERL_  prefix to
+                                           # LC_ALL
 }
 close(CFG);