--- a/src/test/perl/PostgreSQL/Test/Cluster.pm
+++ b/src/test/perl/PostgreSQL/Test/Cluster.pm
@@ -1570,7 +1570,7 @@ sub can_bind
     my ($host, $port) = @_;
     my $iaddr = inet_aton($host);
     my $paddr = sockaddr_in($port, $iaddr);
-   my $proto = getprotobyname("tcp");
+   my $proto = getprotobyname("tcp") || 6;

     socket(SOCK, PF_INET, SOCK_STREAM, $proto)
       or die "socket failed: $!";