diff --git a/src/components/views/dialogs/InviteDialog.tsx b/src/components/views/dialogs/InviteDialog.tsx
index 62536acfd6..81a403bacf 100644
--- a/src/components/views/dialogs/InviteDialog.tsx
+++ b/src/components/views/dialogs/InviteDialog.tsx
@@ -358,20 +358,22 @@ export default class InviteDialog extends React.PureComponent<Props, IInviteDial
         }
 
         this.profilesStore = SdkContextClass.instance.userProfilesStore;
+        const cli = MatrixClientPeg.safeGet();
 
-        const excludedIds = new Set([MatrixClientPeg.safeGet().getUserId()!]);
+        const excludedIds = new Set([cli.getSafeUserId()]);
         if (isRoomInvite(props)) {
-            const room = MatrixClientPeg.safeGet().getRoom(props.roomId);
-            const isFederated = room?.currentState.getStateEvents(EventType.RoomCreate, "")?.getContent()["m.federate"];
+            const room = cli.getRoom(props.roomId);
             if (!room) throw new Error("Room ID given to InviteDialog does not look like a room");
+            const isFederated = room?.currentState.getStateEvents(EventType.RoomCreate, "")?.getContent()["m.federate"];
             room.getMembersWithMembership(KnownMembership.Invite).forEach((m) => excludedIds.add(m.userId));
             room.getMembersWithMembership(KnownMembership.Join).forEach((m) => excludedIds.add(m.userId));
             // add banned users, so we don't try to invite them
             room.getMembersWithMembership(KnownMembership.Ban).forEach((m) => excludedIds.add(m.userId));
-            if (isFederated === false) {
+            const ourHomeserver = cli.getDomain();
+            if (isFederated === false && ourHomeserver) {
+                // If this room isn't federated, we must be on the same server.
                 // exclude users from external servers
-                const homeserver = props.roomId.split(":")[1];
-                this.excludeExternals(homeserver, excludedIds);
+                this.excludeExternals(ourHomeserver, excludedIds);
             }
         }
 
@@ -385,7 +387,7 @@ export default class InviteDialog extends React.PureComponent<Props, IInviteDial
             numSuggestionsShown: INITIAL_ROOMS_SHOWN,
             serverResultsMixin: [],
             threepidResultsMixin: [],
-            canUseIdentityServer: !!MatrixClientPeg.safeGet().getIdentityServerUrl(),
+            canUseIdentityServer: !!cli.getIdentityServerUrl(),
             tryingIdentityServer: false,
             consultFirst: false,
             dialPadValue: "",
diff --git a/test/unit-tests/components/views/dialogs/InviteDialog-test.tsx b/test/unit-tests/components/views/dialogs/InviteDialog-test.tsx
index 02d0d8dd2e..8777d7cb80 100644
--- a/test/unit-tests/components/views/dialogs/InviteDialog-test.tsx
+++ b/test/unit-tests/components/views/dialogs/InviteDialog-test.tsx
@@ -72,6 +72,7 @@ const expectNoPill = (value: string) => {
     expect(getSearchField()).toHaveValue(value);
 };
 
+const serverDomain = "example.org";
 const roomId = "!111111111111111111:example.org";
 const aliceId = "@alice:example.org";
 const aliceEmail = "foobar@email.com";
@@ -103,6 +104,7 @@ describe("InviteDialog", () => {
 
     beforeEach(() => {
         mockClient = getMockClientWithEventEmitter({
+            getDomain: jest.fn().mockReturnValue(serverDomain),
             getUserId: jest.fn().mockReturnValue(bobId),
             getSafeUserId: jest.fn().mockReturnValue(bobId),
             isGuest: jest.fn().mockReturnValue(false),