diff --git a/src/test/modules/test_misc/t/003_check_guc.pl b/src/test/modules/test_misc/t/003_check_guc.pl
index 60459ef759e..1786cd19299 100644
--- a/src/test/modules/test_misc/t/003_check_guc.pl
+++ b/src/test/modules/test_misc/t/003_check_guc.pl
@@ -33,10 +33,9 @@ my $not_in_sample = $node->safe_psql(
      ORDER BY 1");
 my @not_in_sample_array = split("\n", lc($not_in_sample));
 
-# TAP tests are executed in the directory of the test, in the source tree,
-# even for VPATH builds, so rely on that to find postgresql.conf.sample.
-my $rootdir     = "../../../..";
-my $sample_file = "$rootdir/src/backend/utils/misc/postgresql.conf.sample";
+# use the sample file from the temp install
+my $share_dir = $node->config_data('--sharedir');
+my $sample_file = "$share_dir/postgresql.conf.sample";
 
 # List of all the GUCs found in the sample file.
 my @gucs_in_file;