diff --git a/src/test/recovery/t/046_checkpoint_logical_slot.pl b/src/test/recovery/t/046_checkpoint_logical_slot.pl
index d67c5108d78..e8d09842e7e 100644
--- a/src/test/recovery/t/046_checkpoint_logical_slot.pl
+++ b/src/test/recovery/t/046_checkpoint_logical_slot.pl
@@ -116,12 +116,14 @@ $node->safe_psql('postgres',
 	q{select pg_replication_slot_advance('slot_physical', pg_current_wal_lsn())}
 );
 
-# Continue the checkpoint.
+# Continue the checkpoint and wait for its finish.
+my $log_offset = -s $node->logfile;
 $node->safe_psql('postgres',
 	q{select injection_points_wakeup('checkpoint-before-old-wal-removal')});
+	# Confirm that the slot sync worker is able to start.
+$node->wait_for_log(qr/checkpoint complete:/, $log_offset);
 
-# Abruptly stop the server (1 second should be enough for the checkpoint
-# to finish; it would be better).
+# Abruptly stop the server.
 $node->stop('immediate');
 
 $node->start;
diff --git a/src/test/recovery/t/047_checkpoint_physical_slot.pl b/src/test/recovery/t/047_checkpoint_physical_slot.pl
index a1332b5d44c..a0d6963c947 100644
--- a/src/test/recovery/t/047_checkpoint_physical_slot.pl
+++ b/src/test/recovery/t/047_checkpoint_physical_slot.pl
@@ -94,9 +94,12 @@ $node->safe_psql('postgres',
 	q{select pg_replication_slot_advance('slot_physical', pg_current_wal_lsn())}
 );
 
-# Continue the checkpoint.
+# Continue the checkpoint and wait for its finish.
+my $log_offset = -s $node->logfile;
 $node->safe_psql('postgres',
 	q{select injection_points_wakeup('checkpoint-before-old-wal-removal')});
+	# Confirm that the slot sync worker is able to start.
+$node->wait_for_log(qr/checkpoint complete:/, $log_offset);
 
 my $restart_lsn_old = $node->safe_psql('postgres',
 	q{select restart_lsn from pg_replication_slots where slot_name = 'slot_physical'}
@@ -104,8 +107,7 @@ my $restart_lsn_old = $node->safe_psql('postgres',
 chomp($restart_lsn_old);
 note("restart lsn before stop: $restart_lsn_old");
 
-# Abruptly stop the server (1 second should be enough for the checkpoint
-# to finish; it would be better).
+# Abruptly stop the server.
 $node->stop('immediate');
 
 $node->start;