diff --git a/pg_upgradecluster b/pg_upgradecluster
index 61fd0dd..cd8e430 100755
--- a/pg_upgradecluster
+++ b/pg_upgradecluster
@@ -338,9 +338,11 @@ if (!fork) {
     my $buffer;
 
     # check for tablespaces (not supported)
-    open F, '-|', $oldpsql, '-h', $oldsocket, '-d', 'template1', '-Atc', 
-            "SELECT count(*) FROM pg_tablespace WHERE spcname <> 'pg_default' AND spcname <> 'pg_global'"
-	or die "Calling $psql: $!";
+    open F, '-|', $oldpsql, '-h', $oldsocket, , '-p', $info{'port'},
+        '-d', 'template1', '-Atc',
+        "SELECT count(*) FROM pg_tablespace WHERE spcname <> 'pg_default' AND spcname <> 'pg_global'"
+    or die "Calling $psql: $!";
+
     $buffer = <F>;
     close F;
     if ($buffer ne "0\n") {