--- a/Extensions.cs
+++ b/Extensions.cs
@@ -34,7 +34,7 @@
 		/// </summary>
 		/// <param name="relay">This <see cref="IAntennaRelay"/></param>
 		/// <param name="Vessel">A <see cref="Vessel"/></param>
-		public static double DistanceTo(this IAntennaRelay relay, Vessel Vessel)
+		public static double DistanceTo(this AntennaRelay relay, Vessel Vessel)
 		{
 			return relay.vessel.DistanceTo(Vessel);
 		}
@@ -44,7 +44,7 @@
 		/// </summary>
 		/// <param name="relay">This <see cref="IAntennaRelay"/></param>
 		/// <param name="body">A <see cref="CelestialBody"/></param>
-		public static double DistanceTo(this IAntennaRelay relay, CelestialBody body)
+		public static double DistanceTo(this AntennaRelay relay, CelestialBody body)
 		{
 			return relay.vessel.DistanceTo(body);
 		}
@@ -54,7 +54,7 @@
 		/// </summary>
 		/// <param name="relayOne">This <see cref="IAntennaRelay"/></param>
 		/// <param name="relayTwo">Another <see cref="IAntennaRelay"/></param>
-		public static double DistanceTo(this IAntennaRelay relayOne, IAntennaRelay relayTwo)
+		public static double DistanceTo(this AntennaRelay relayOne, IAntennaRelay relayTwo)
 		{
 			return relayOne.DistanceTo(relayTwo.vessel);
 		}