diff -up AnyEvent-7.13/Makefile.PL.orig AnyEvent-7.13/Makefile.PL
--- AnyEvent-7.13/Makefile.PL.orig	2017-05-17 14:33:30.966186261 +0200
+++ AnyEvent-7.13/Makefile.PL	2017-05-17 14:34:13.414007081 +0200
@@ -22,7 +22,7 @@ print <<EOF;
 
 EOF
 
-do "constants.pl.PL"
+do "./constants.pl.PL"
    or die "cannot execute constants.pl.PL: $@";
 
 WriteMakefile(