diff --git a/ip/tcp_metrics.c b/ip/tcp_metrics.c
index 34e1d8e..a01e1fb 100644
--- a/ip/tcp_metrics.c
+++ b/ip/tcp_metrics.c
@@ -268,7 +268,7 @@
 	case AF_INET6:
 		break;
 	default:
-		fprintf(stderr, "Unsupported family:%d\n", preferred_family);
+		fprintf(stderr, "Unsupported protocol family: %d\n", preferred_family);
 		return -1;
 	}