diff --git a/vector/src/main/java/im/vector/riotx/core/extensions/Set.kt b/vector/src/main/java/im/vector/riotx/core/extensions/Set.kt
new file mode 100644
index 0000000000..43eb1b0d7c
--- /dev/null
+++ b/vector/src/main/java/im/vector/riotx/core/extensions/Set.kt
@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2020 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.riotx.core.extensions
+
+// Create a new Set including the provided element if not already present, or removing the element if already present
+fun <T> Set<T>.toggle(element: T): Set<T> {
+    return if (contains(element)) {
+        minus(element)
+    } else {
+        plus(element)
+    }
+}
diff --git a/vector/src/main/java/im/vector/riotx/features/share/IncomingShareViewModel.kt b/vector/src/main/java/im/vector/riotx/features/share/IncomingShareViewModel.kt
index 8a425d70d4..c135460ee4 100644
--- a/vector/src/main/java/im/vector/riotx/features/share/IncomingShareViewModel.kt
+++ b/vector/src/main/java/im/vector/riotx/features/share/IncomingShareViewModel.kt
@@ -29,6 +29,7 @@ import im.vector.matrix.android.api.session.room.model.Membership
 import im.vector.matrix.android.api.session.room.roomSummaryQueryParams
 import im.vector.matrix.rx.rx
 import im.vector.riotx.core.extensions.exhaustive
+import im.vector.riotx.core.extensions.toggle
 import im.vector.riotx.core.platform.VectorViewModel
 import im.vector.riotx.features.attachments.isPreviewable
 import im.vector.riotx.features.attachments.toGroupedContentAttachmentData
@@ -180,11 +181,7 @@ class IncomingShareViewModel @AssistedInject constructor(
         if (state.isInMultiSelectionMode) {
             // One room is clicked (or long clicked) while in multi selection mode -> toggle this room
             val selectedRooms = state.selectedRoomIds
-            val newSelectedRooms = if (selectedRooms.contains(action.roomSummary.roomId)) {
-                selectedRooms.minus(action.roomSummary.roomId)
-            } else {
-                selectedRooms.plus(action.roomSummary.roomId)
-            }
+            val newSelectedRooms = selectedRooms.toggle(action.roomSummary.roomId)
             setState { copy(isInMultiSelectionMode = newSelectedRooms.isNotEmpty(), selectedRoomIds = newSelectedRooms) }
         } else if (action.enableMultiSelect) {
             // One room is long clicked, not in multi selection mode -> enable multi selection mode