diff --git a/lib/PerconaTest.pm b/lib/PerconaTest.pm
index 5d41d08f..40175e6e 100644
--- a/lib/PerconaTest.pm
+++ b/lib/PerconaTest.pm
@@ -236,6 +236,26 @@ sub wait_until {
    return 0;
 }
 
+sub wait_until_no_lag {
+   my (@dbhs) = @_;
+   foreach my $dbh (@dbhs) {
+      PTDEVDEBUG && _d('Waiting for no slave lag');
+      wait_until(  # slaves aren't lagging
+         sub {
+            my $row = $dbh->selectrow_hashref('SHOW SLAVE STATUS');
+            my $lag = exists $row->{Seconds_Behind_Master}
+                    ? $row->{Seconds_Behind_Master}
+                    : $row->{seconds_behind_master};
+            PTDEVDEBUG && _d('Slave lag:', $lag);
+            if ( !defined $lag ) {
+               BAIL_OUT("Slave is stopped: " . Dumper($row));
+            }
+            return $lag ? 0 : 1;
+         }
+      );
+   }
+}
+
 # Wait t seconds for code to return.
 sub wait_for {
    my ( $code, $t ) = @_;
diff --git a/sandbox/test-env b/sandbox/test-env
index 26558d29..54bea934 100755
--- a/sandbox/test-env
+++ b/sandbox/test-env
@@ -354,18 +354,16 @@ case $opt in
       # don't replicate to new sandbox servers.  This makes creating new
       # sandbox servers a lot faster.  There's no check if this works or
       # not, so... yeah.
-      /tmp/12347/use -e "STOP SLAVE"
-      /tmp/12346/use -e "STOP SLAVE"
+      /tmp/12347/use -e "STOP SLAVE; FLUSH SLAVE;"
+      /tmp/12346/use -e "STOP SLAVE; FLUSH SLAVE; FLUSH MASTER;"
+      /tmp/12345/use -e "FLUSH MASTER"
 
-      /tmp/12346/use -e "RESET MASTER"
-      /tmp/12345/use -e "RESET MASTER"
-
-      /tmp/12347/use -e "change master to master_host='127.0.0.1', master_user='msandbox', master_password='msandbox', master_port=12346, master_log_file='mysql-bin.000001', master_log_pos=0"
-      /tmp/12346/use -e "change master to master_host='127.0.0.1', master_user='msandbox', master_password='msandbox', master_port=12345, master_log_file='mysql-bin.000001', master_log_pos=0"
-
-      /tmp/12347/use -e "START SLAVE"
+      /tmp/12346/use -e "CHANGE MASTER TO master_host='127.0.0.1', master_user='msandbox', master_password='msandbox', master_port=12345, master_log_file='mysql-bin.000001', master_log_pos=0"
       /tmp/12346/use -e "START SLAVE"
 
+      /tmp/12347/use -e "CHANGE MASTER TO master_host='127.0.0.1', master_user='msandbox', master_password='msandbox', master_port=12346, master_log_file='mysql-bin.000001', master_log_pos=0"
+      /tmp/12347/use -e "START SLAVE"
+
       exit_status=0
       ;;
    version)
diff --git a/t/pt-table-checksum/basics.t b/t/pt-table-checksum/basics.t
index 0fe30d17..a110c6eb 100644
--- a/t/pt-table-checksum/basics.t
+++ b/t/pt-table-checksum/basics.t
@@ -61,6 +61,7 @@ sub reset_repl_db {
    $master_dbh->do("use $repl_db");
 }
 
+diag(`$trunk/sandbox/test-env reset >/dev/null`);
 $sb->wipe_clean($master_dbh);
 diag(`rm $outfile >/dev/null 2>&1`);
 
diff --git a/t/pt-table-checksum/progress.t b/t/pt-table-checksum/progress.t
index a08070a8..812cf755 100644
--- a/t/pt-table-checksum/progress.t
+++ b/t/pt-table-checksum/progress.t
@@ -42,8 +42,6 @@ else {
    plan tests => 4;
 }
 
-# Must have empty checksums table for these tests.
-$master_dbh->do('drop table if exists percona.checksums');
 
 # The sandbox servers run with lock_wait_timeout=3 and it's not dynamic
 # so we need to specify --lock-wait-timeout=3 else the tool will die.
@@ -58,15 +56,12 @@ my $scripts = "$trunk/t/pt-table-checksum/scripts/";
 # ############################################################################
 # Tool should check all slaves' lag, so slave2, not just slave1.
 # ############################################################################
-wait_until(  # slaves aren't lagging
-   sub {
-      $row = $slave1_dbh->selectrow_hashref('show slave status');
-      return 0 if $row->{Seconds_Behind_Master};
-      $row = $slave2_dbh->selectrow_hashref('show slave status');
-      return 0 if $row->{Seconds_Behind_Master};
-      return 1;
-   }
-) or die "Slaves are still lagging";
+
+# Must have empty checksums table for these tests.
+$master_dbh->do('drop table if exists percona.checksums');
+
+# Must not be lagging.
+PerconaTest::wait_until_no_lag($slave1_dbh, $slave2_dbh);
 
 # This big fancy command waits until it sees the checksum for sakila.city
 # in the repl table on the master, then it stops slave2 for 2 seconds,
@@ -100,6 +95,5 @@ is(
 # Done.
 # #############################################################################
 $sb->wipe_clean($master_dbh);
-diag(`$trunk/sandbox/test-env reset >/dev/null`);
 ok($sb->ok(), "Sandbox servers") or BAIL_OUT(__FILE__ . " broke the sandbox");
 exit;
diff --git a/t/pt-table-checksum/replication_filters.t b/t/pt-table-checksum/replication_filters.t
index 4a716720..29600db1 100644
--- a/t/pt-table-checksum/replication_filters.t
+++ b/t/pt-table-checksum/replication_filters.t
@@ -52,22 +52,36 @@ my @args       = ($master_dsn, qw(--lock-wait-timeout 3), '--max-load', '');
 my $output;
 my $row;
 
+# You must call this sub if the master 12345 or slave1 12346 is restarted,
+# else a slave might notice that its master went away and enter the "trying
+# to reconnect" state, and then replication will break as the tests continue.
+sub reset_slaves {
+   $slave1_dbh->do('STOP SLAVE');
+   $slave2_dbh->do('STOP SLAVE');
+   $slave1_dbh->do('START SLAVE');
+   $slave2_dbh->do('START SLAVE');
+}
+
+# #############################################################################
+# Repl filters on all slaves, at all depths, should be found.
+# #############################################################################
+
 # Add a replication filter to the slaves.
+diag(`/tmp/12347/stop >/dev/null`);
+diag(`/tmp/12346/stop >/dev/null`);
 for my $port ( qw(12346 12347) ) {
-   diag(`/tmp/$port/stop >/dev/null`);
    diag(`cp /tmp/$port/my.sandbox.cnf /tmp/$port/orig.cnf`);
    diag(`echo "replicate-ignore-db=foo" >> /tmp/$port/my.sandbox.cnf`);
    diag(`/tmp/$port/start >/dev/null`);
 }
 $slave1_dbh = $sb->get_dbh_for('slave1');
 $slave2_dbh = $sb->get_dbh_for('slave2');
-$sb->ok() or BAIL_OUT("Sandbox is broken");
 
 my $pos = PerconaTest::get_master_binlog_pos($master_dbh);
 
 $output = output(
    sub { pt_table_checksum::main(@args, qw(-t sakila.country)) },
-   #stderr => 1,
+   stderr => 1,
 );
 
 is(
@@ -92,7 +106,7 @@ like(
 $output = output(
    sub { pt_table_checksum::main(@args, qw(-t sakila.country),
       qw(--no-check-replication-filters)) },
-   #stderr => 1,
+   stderr => 1,
 );
 
 like(
@@ -102,8 +116,9 @@ like(
 );
 
 # Remove the replication filter from the slave.
+diag(`/tmp/12347/stop >/dev/null`);
+diag(`/tmp/12346/stop >/dev/null`);
 for my $port ( qw(12346 12347) ) {
-   diag(`/tmp/$port/stop >/dev/null`);
    diag(`mv /tmp/$port/orig.cnf /tmp/$port/my.sandbox.cnf`);
    diag(`/tmp/$port/start >/dev/null`);
 }
@@ -120,21 +135,14 @@ pt_table_checksum::main(@args, qw(--chunk-time 0 --chunk-size 100),
    '-t', 'mysql.user,sakila.city', qw(--quiet));
 PerconaTest::wait_for_table($slave1_dbh, 'percona.checksums', "db='sakila' and tbl='city' and chunk=6");
 
+# Add a replication filter to the master: ignore db mysql.
 $master_dbh->disconnect();
-$slave1_dbh->disconnect();
-
-# Add a replication filter to the slave: ignore db mysql.
-diag(`/tmp/12346/stop >/dev/null`);
 diag(`/tmp/12345/stop >/dev/null`);
-
 diag(`cp /tmp/12345/my.sandbox.cnf /tmp/12345/orig.cnf`);
 diag(`echo "binlog-ignore-db=mysql" >> /tmp/12345/my.sandbox.cnf`);
-
 diag(`/tmp/12345/start >/dev/null`);
-diag(`/tmp/12346/start >/dev/null`);
+reset_slaves();
 $master_dbh = $sb->get_dbh_for('master');
-$slave1_dbh = $sb->get_dbh_for('slave1');
-$sb->ok() or BAIL_OUT("Sandbox is broken");
 
 # Checksum the tables again in 1 chunk.  Since db percona isn't being
 # ignored, deleting old results in the repl table should replicate.
@@ -157,38 +165,30 @@ $master_dbh->do("use percona");
 $master_dbh->do("truncate table percona.checksums");
 wait_until(
    sub {
-      $row = $slave1_dbh->selectall_arrayref("select * from percona.checksums");
+      $row=$slave1_dbh->selectall_arrayref("select * from percona.checksums");
       return !@$row;
    }
 );
 
-$master_dbh->disconnect();
-$slave1_dbh->disconnect();
-
-# Restore original config.
-diag(`/tmp/12346/stop >/dev/null`);
-diag(`/tmp/12345/stop >/dev/null`);
-diag(`cp /tmp/12345/orig.cnf /tmp/12345/my.sandbox.cnf`);
-
 # #############################################################################
 # Test --replicate-database which resulted from this issue.
 # #############################################################################
 
-# Add a binlog-do-db filter so master will only replicate
-# statements when USE mysql is in effect.
+# Restore original config.  Then add a binlog-do-db filter so master
+# will only replicate statements when USE mysql is in effect.
+$master_dbh->disconnect();
+diag(`/tmp/12345/stop >/dev/null`);
+diag(`cp /tmp/12345/orig.cnf /tmp/12345/my.sandbox.cnf`);
 diag(`echo "binlog-do-db=mysql" >> /tmp/12345/my.sandbox.cnf`);
 diag(`/tmp/12345/start >/dev/null`);
-diag(`/tmp/12346/start >/dev/null`);
-
 $master_dbh = $sb->get_dbh_for('master');
-$slave1_dbh = $sb->get_dbh_for('slave1');
-$sb->ok() or BAIL_OUT("Sandbox is broken");
+reset_slaves();
 
 $output = output(
    sub { pt_table_checksum::main(@args, qw(--no-check-replication-filters),
       qw(-d mysql -t user))
    },
-   #stderr => 1,
+   stderr => 1,
 );
 
 # Because we did not use --replicate-database, pt-table-checksum should
@@ -208,7 +208,7 @@ $master_dbh->do("use mysql");
 $master_dbh->do("truncate table percona.checksums");
 wait_until(
    sub {
-      $row = $slave1_dbh->selectall_arrayref("select * from percona.checksums");
+      $row=$slave1_dbh->selectall_arrayref("select * from percona.checksums");
       return !@$row;
    }
 );
@@ -233,22 +233,18 @@ is(
 );
 
 # #############################################################################
-# Restore original config.
+# Check that only the expected dbs are used.
 # #############################################################################
-$master_dbh->disconnect();
-$slave1_dbh->disconnect();
 
-diag(`/tmp/12346/stop >/dev/null`);
+# Restore the original config.
+$master_dbh->disconnect();
 diag(`/tmp/12345/stop >/dev/null`);
 diag(`mv /tmp/12345/orig.cnf /tmp/12345/my.sandbox.cnf`);
 diag(`/tmp/12345/start >/dev/null`);
-diag(`/tmp/12346/start >/dev/null`);
-
-diag(`$trunk/sandbox/test-env reset`);
-
 $master_dbh = $sb->get_dbh_for('master');
-$slave1_dbh = $sb->get_dbh_for('slave1');
-$sb->ok() or BAIL_OUT("Sandbox is broken");
+
+# Reset the slaves and clear the binlogs.
+diag(`$trunk/sandbox/test-env reset`);
 
 pt_table_checksum::main(@args, qw(--quiet));
 
@@ -264,6 +260,7 @@ use sakila/*!*/;
    "USE each table's database (binlog dump)"
 );
 
+# Clear the binlogs.
 diag(`$trunk/sandbox/test-env reset`);
 
 pt_table_checksum::main(@args, qw(--quiet --replicate-database percona));
@@ -276,16 +273,6 @@ is(
    "USE only --replicate-database (binlog dump)"
 );
 
-# #############################################################################
-# Stop and start slaves to avoid sandbox breakage caused by restarting servers.
-# #############################################################################
-#$slave1_dbh = $sb->get_dbh_for('slave1');
-#$slave2_dbh = $sb->get_dbh_for('slave2');
-#$slave1_dbh->do('STOP SLAVE');
-#$slave2_dbh->do('STOP SLAVE');
-#$slave1_dbh->do('START SLAVE');
-#$slave2_dbh->do('START SLAVE');
-
 # #############################################################################
 # Done.
 # #############################################################################