diff --git a/src/github.com/matrix-org/dendrite/roomserver/input/membership.go b/src/github.com/matrix-org/dendrite/roomserver/input/membership.go
index 7651e7c3c..d693e40fe 100644
--- a/src/github.com/matrix-org/dendrite/roomserver/input/membership.go
+++ b/src/github.com/matrix-org/dendrite/roomserver/input/membership.go
@@ -32,11 +32,11 @@ func updateMemberships(
 	changes := membershipChanges(removed, added)
 	var eventNIDs []types.EventNID
 	for _, change := range changes {
-		if change.added.EventNID != 0 {
-			eventNIDs = append(eventNIDs, change.added.EventNID)
+		if change.addedEventNID != 0 {
+			eventNIDs = append(eventNIDs, change.addedEventNID)
 		}
-		if change.removed.EventNID != 0 {
-			eventNIDs = append(eventNIDs, change.removed.EventNID)
+		if change.removedEventNID != 0 {
+			eventNIDs = append(eventNIDs, change.removedEventNID)
 		}
 	}
 
@@ -53,20 +53,18 @@ func updateMemberships(
 	for _, change := range changes {
 		var ae *gomatrixserverlib.Event
 		var re *gomatrixserverlib.Event
-		var targetUserNID types.EventStateKeyNID
-		if change.removed.EventNID != 0 {
-			ev, _ := eventMap(events).lookup(change.removed.EventNID)
+		targetUserNID := change.EventStateKeyNID
+		if change.removedEventNID != 0 {
+			ev, _ := eventMap(events).lookup(change.removedEventNID)
 			if ev != nil {
 				re = &ev.Event
 			}
-			targetUserNID = change.removed.EventStateKeyNID
 		}
-		if change.added.EventNID != 0 {
-			ev, _ := eventMap(events).lookup(change.added.EventNID)
+		if change.addedEventNID != 0 {
+			ev, _ := eventMap(events).lookup(change.addedEventNID)
 			if ev != nil {
 				ae = &ev.Event
 			}
-			targetUserNID = change.added.EventStateKeyNID
 		}
 		if updates, err = updateMembership(updater, targetUserNID, re, ae, updates); err != nil {
 			return nil, err
@@ -222,8 +220,7 @@ func membershipChanges(removed, added []types.StateEntry) []stateChange {
 	changes := pairUpChanges(removed, added)
 	var result []stateChange
 	for _, c := range changes {
-		if c.added.EventTypeNID == types.MRoomMemberNID ||
-			c.removed.EventTypeNID == types.MRoomMemberNID {
+		if c.EventTypeNID == types.MRoomMemberNID {
 			result = append(result, c)
 		}
 	}
@@ -231,8 +228,9 @@ func membershipChanges(removed, added []types.StateEntry) []stateChange {
 }
 
 type stateChange struct {
-	removed types.StateEntry
-	added   types.StateEntry
+	types.StateKeyTuple
+	removedEventNID types.EventNID
+	addedEventNID   types.EventNID
 }
 
 // pairUpChanges pairs up the state events added and removed for each type,
@@ -245,26 +243,40 @@ func pairUpChanges(removed, added []types.StateEntry) []stateChange {
 		switch {
 		case ai == len(added):
 			for _, s := range removed[ri:] {
-				result = append(result, stateChange{removed: s})
+				result = append(result, stateChange{
+					StateKeyTuple:   s.StateKeyTuple,
+					removedEventNID: s.EventNID,
+				})
 			}
 			return result
 		case ri == len(removed):
 			for _, s := range added[ai:] {
-				result = append(result, stateChange{added: s})
+				result = append(result, stateChange{
+					StateKeyTuple: s.StateKeyTuple,
+					addedEventNID: s.EventNID,
+				})
 			}
 			return result
 		case added[ai].StateKeyTuple == removed[ri].StateKeyTuple:
 			result = append(result, stateChange{
-				removed: removed[ri],
-				added:   added[ai],
+				StateKeyTuple:   added[ai].StateKeyTuple,
+				removedEventNID: removed[ri].EventNID,
+				addedEventNID:   added[ai].EventNID,
 			})
 			ai++
 			ri++
 		case added[ai].StateKeyTuple.LessThan(removed[ri].StateKeyTuple):
-			result = append(result, stateChange{added: added[ai]})
+			result = append(result, stateChange{
+
+				StateKeyTuple: added[ai].StateKeyTuple,
+				addedEventNID: added[ai].EventNID,
+			})
 			ai++
 		default:
-			result = append(result, stateChange{removed: removed[ri]})
+			result = append(result, stateChange{
+				StateKeyTuple:   removed[ai].StateKeyTuple,
+				removedEventNID: removed[ri].EventNID,
+			})
 			ri++
 		}
 	}