diff --git a/t/harness b/t/harness
index 50e5e899b071..8077abe6a1f6 100644
--- a/t/harness
+++ b/t/harness
@@ -22,6 +22,8 @@ BEGIN {
 # Example: ../cpan/IO-Zlib/t/basic.t
 #
 my @_must_be_executed_serially = qw(
+                                    ../dist/Tie-File/t/24_cache_loop.t
+                                    ../ext/File-Find/t/taint.t
 );
 my %must_be_executed_serially = map { $_ => 1 } @_must_be_executed_serially;
 ##############################################################################
@@ -35,16 +37,18 @@ my %must_be_executed_serially = map { $_ => 1 } @_must_be_executed_serially;
 #
 # Example: ../dist/threads-shared/t/waithires.t
 #
-my @_must_be_executed_alone = qw();
+my @_must_be_executed_alone = qw(
+                                 re/speed_thr.t
+                                  ../dist/Tie-File/t/29a_upcopy.t
+                                );
+push @_must_be_executed_alone, "../dist/threads-shared/t/waithires.t"
+                                                            if $^O ne "linux";
 my %must_be_executed_alone = map { $_ => 1 } @_must_be_executed_alone;
 
 my $OS = $ENV{FAKE_OS} || $^O;
 my $is_linux = $OS eq "linux";
 my $is_win32 = $OS eq "MSWin32";
 
-if (!$is_linux) {
-    $must_be_executed_alone{"../dist/threads-shared/t/waithires.t"} = 1;
-}
 ##############################################################################
 
 my $torture; # torture testing?