--- a/regress/run_test.pl
+++ b/regress/run_test.pl
@@ -709,7 +709,8 @@ sub run_simple_test
 		# TODO: allow override this default with env variable ?
 		my $pgis_majmin = $libver;
 		$pgis_majmin =~ s/^([1-9]*\.[1-9]*).*/\1/;
-		$scriptdir = `pg_config --sharedir`;
+		my $PG_CONFIG = $ENV{PG_CONFIG} // 'pg_config';
+		$scriptdir = `$PG_CONFIG --sharedir`;
 		chop $scriptdir;
 		$scriptdir .= "/contrib/postgis-" . $pgis_majmin;
 	} else {
