MANIFEST            | 1 +
 devel/longest-tests | 7 +++++++
 t/run.perl          | 4 ++++

diff --git a/MANIFEST b/MANIFEST
index f22f60aa217fa6b95825830a81cf0bfc64e6b47c..aba32762a4073b2018684e1dfcd0e542266dacae 100644
--- a/MANIFEST
+++ b/MANIFEST
@@ -121,6 +121,7 @@ contrib/css/README
 contrib/selinux/el7/publicinbox.fc
 contrib/selinux/el7/publicinbox.te
 devel/README
+devel/longest-tests
 devel/syscall-list
 examples/README
 examples/README.unsubscribe
diff --git a/devel/longest-tests b/devel/longest-tests
new file mode 100755
index 0000000000000000000000000000000000000000..bf46e1660875e6501efdaa66e360bc9f57fa3fff
--- /dev/null
+++ b/devel/longest-tests
@@ -0,0 +1,7 @@
+eval 'exec perl -wS $0 ${1+"$@"}' # this script is too short to copyright
+if 0; # running under some shell
+use v5.12; use autodie; use YAML::XS qw(Load);
+open(my $fh, '<', shift // '.prove');
+my $t = Load(do { local $/; <$fh> })->{tests};
+my @t = sort { $t->{$b}->{elapsed} <=> $t->{$a}->{elapsed} } keys %$t;
+printf "%0.6f %s\n", $t->{$_}->{elapsed}, $_ for @t;
diff --git a/t/run.perl b/t/run.perl
index b90715a6ffe09ce86d04e84ad7d7b1f5b71c604d..f68dab607f2693c53edb9d517b9ff93150fbae5a 100755
--- a/t/run.perl
+++ b/t/run.perl
@@ -85,6 +85,10 @@ 	my $t = $state->{tests};
 	@tests = sort {
 		($t->{$b}->{elapsed} // 0) <=> ($t->{$a}->{elapsed} // 0)
 	} @tests;
+	say "# top 10 longest tests (`make check' regenerates)";
+	for (@tests[0..9]) {
+		printf "# %0.6f %s\n", $t->{$_}->{elapsed}, $_;
+	}
 }
 
 our $tb = Test::More->builder;