diff --git a/src/refit/replica/client/REFITClientStage.java b/src/refit/replica/client/REFITClientStage.java
index a29fbb23e108ab4309fd0bb8627b93eed29b8264..8e2f5beee01620c39c4273624a48f3242d8a4d86 100644
--- a/src/refit/replica/client/REFITClientStage.java
+++ b/src/refit/replica/client/REFITClientStage.java
@@ -212,6 +212,10 @@ public class REFITClientStage extends REFITStage {
 		case CONFIGURATION_NOTIFICATION:
 			REFITConfigurationNotification notification = (REFITConfigurationNotification) instruction;
 			int limitedGroupID = Math.max(0, groupID);
+			if (limitedGroupID != notification.groupID) {
+				throw new InternalError("Got configuration for unexpected group " + notification.groupID);
+			}
+
 			REFITOrderProtocol protocol = notification.protocol;
 			sendReplies = protocol.getActiveOrderRecipients(limitedGroupID)[replica.id];
 			contactReplica = REFITOrderGroups.getGroupPrimary(notification.groupID, notification.viewID);