diff --git a/meson.build b/meson.build
index 574f992ed49..13c13748e5d 100644
--- a/meson.build
+++ b/meson.build
@@ -3401,6 +3401,8 @@ test_initdb_template = meson.build_root() / 'tmp_install' / 'initdb-template'
 test_env.set('PG_REGRESS', pg_regress.full_path())
 test_env.set('REGRESS_SHLIB', regress_module.full_path())
 test_env.set('INITDB_TEMPLATE', test_initdb_template)
+# for Cluster.pm's portlock logic
+test_env.set('top_builddir', meson.build_root())
 
 # Add the temporary installation to the library search path on platforms where
 # that works (everything but windows, basically). On windows everything
diff --git a/src/test/perl/PostgreSQL/Test/Cluster.pm b/src/test/perl/PostgreSQL/Test/Cluster.pm
index f31af70edb6..b105cba05a6 100644
--- a/src/test/perl/PostgreSQL/Test/Cluster.pm
+++ b/src/test/perl/PostgreSQL/Test/Cluster.pm
@@ -168,9 +168,7 @@ INIT
 	$portdir = $ENV{PG_TEST_PORT_DIR};
 	# Otherwise, try to use a directory at the top of the build tree
 	# or as a last resort use the tmp_check directory
-	my $build_dir =
-		 $ENV{MESON_BUILD_ROOT}
-	  || $ENV{top_builddir}
+	my $build_dir = $ENV{top_builddir}
 	  || $PostgreSQL::Test::Utils::tmp_check;
 	$portdir ||= "$build_dir/portlock";
 	$portdir =~ s!\\!/!g;