diff --git a/src/test/modules/test_checksums/t/001_basic.pl b/src/test/modules/test_checksums/t/001_basic.pl
index 4cfa35b6885..4cfd532500d 100644
--- a/src/test/modules/test_checksums/t/001_basic.pl
+++ b/src/test/modules/test_checksums/t/001_basic.pl
@@ -172,8 +172,13 @@ $node->safe_psql('dropmeforce',
 	"CREATE TABLE dropme_t AS SELECT generate_series(1,10000) AS a;");
 
 # Hold the worker inside "dropmeforce" by keeping a temporary table around
-# there.
+# there.  The session is later terminated by DROP DATABASE ... WITH (FORCE)
+# and drops the temp table while exiting; commit that drop asynchronously,
+# otherwise the exit has to flush WAL behind the traffic generated by the
+# checksum workers, which on slow machines can exceed the time DROP DATABASE
+# waits for the session to exit.
 $bg = $node->background_psql('dropmeforce');
+$bg->query_safe('SET synchronous_commit = off;');
 $bg->query_safe('CREATE TEMP TABLE holdme (a int);');
 
 enable_data_checksums($node);
@@ -185,6 +190,11 @@ $node->poll_query_until(
 	  AND query LIKE 'Waiting for % temp tables to be removed']
 ) or die "timed out waiting for worker to wait for temporary tables";
 
+# Write out the WAL backlog from the checksum processing so far, so that the
+# sessions terminated below do not get stuck behind it when writing their
+# final WAL records on slow machines.
+$node->safe_psql('postgres', "CHECKPOINT;");
+
 # Terminates both the session holding the temp table and the checksums
 # worker connected to the database.
 $node->safe_psql('postgres', "DROP DATABASE dropmeforce WITH (FORCE);");