Makefile.PL | 2 +-

diff --git a/Makefile.PL b/Makefile.PL
index f6b7abb65647164193f576a78fb688f9593212e5..c834910cb1a9fec7f8511f0bd6b58ebe97dd0093 100644
--- a/Makefile.PL
+++ b/Makefile.PL
@@ -107,7 +107,7 @@ 	my $base = $_;
 	my $mod = $base;
 	$mod =~ s!/!::!g;
 	$mod =~ s/\.\w+\z//;
-	"lib/PublicInbox/$_" => "blib/man3/PublicInbox::$mod.3"
+	"lib/PublicInbox/$_" => "blib/man3/PublicInbox::$mod.\$(MAN3EXT)"
 } qw(Git.pm Import.pm WWW.pod SaPlugin/ListMirror.pod);
 
 WriteMakefile(