diff --git a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesView.kt b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesView.kt
index f28ff69905..2da1d64642 100644
--- a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesView.kt
+++ b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/MessagesView.kt
@@ -443,7 +443,7 @@ private fun MessagesViewComposerBottomSheetContents(
 private fun MessagesViewTopBar(
     roomName: String?,
     roomAvatar: AvatarData?,
-    heroes: List<AvatarData>,
+    heroes: ImmutableList<AvatarData>,
     callState: RoomCallState,
     onRoomDetailsClick: () -> Unit,
     onJoinCallClick: () -> Unit,
@@ -503,7 +503,7 @@ private fun CallMenuItem(
 private fun RoomAvatarAndNameRow(
     roomName: String,
     roomAvatar: AvatarData,
-    heroes: List<AvatarData>,
+    heroes: ImmutableList<AvatarData>,
     modifier: Modifier = Modifier
 ) {
     Row(
diff --git a/features/roomdetails/impl/src/main/kotlin/io/element/android/features/roomdetails/impl/RoomDetailsView.kt b/features/roomdetails/impl/src/main/kotlin/io/element/android/features/roomdetails/impl/RoomDetailsView.kt
index a243e34315..1269ff1f4d 100644
--- a/features/roomdetails/impl/src/main/kotlin/io/element/android/features/roomdetails/impl/RoomDetailsView.kt
+++ b/features/roomdetails/impl/src/main/kotlin/io/element/android/features/roomdetails/impl/RoomDetailsView.kt
@@ -26,7 +26,6 @@ import androidx.compose.foundation.layout.consumeWindowInsets
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material.icons.Icons
@@ -85,6 +84,8 @@ import io.element.android.libraries.matrix.api.user.MatrixUser
 import io.element.android.libraries.testtags.TestTags
 import io.element.android.libraries.testtags.testTag
 import io.element.android.libraries.ui.strings.CommonStrings
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.toPersistentList
 
 @Composable
 fun RoomDetailsView(
@@ -326,7 +327,7 @@ private fun RoomHeaderSection(
     roomAlias: RoomAlias?,
     isEncrypted: Boolean,
     isPublic: Boolean,
-    heroes: List<MatrixUser> = emptyList(),
+    heroes: ImmutableList<MatrixUser>,
     openAvatarPreview: (url: String) -> Unit,
 ) {
     Column(
@@ -344,7 +345,7 @@ private fun RoomHeaderSection(
                     url = user.avatarUrl,
                     size = AvatarSize.RoomHeader
                 )
-            },
+            }.toPersistentList(),
             modifier = Modifier
                 .clickable(enabled = avatarUrl != null) { openAvatarPreview(avatarUrl!!) }
                 .testTag(TestTags.roomDetailAvatar)
diff --git a/libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/avatar/CompositeAvatar.kt b/libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/avatar/CompositeAvatar.kt
index ada1671eea..2422f32c92 100644
--- a/libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/avatar/CompositeAvatar.kt
+++ b/libraries/designsystem/src/main/kotlin/io/element/android/libraries/designsystem/components/avatar/CompositeAvatar.kt
@@ -30,6 +30,8 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import io.element.android.libraries.designsystem.preview.ElementThemedPreview
 import io.element.android.libraries.designsystem.preview.PreviewGroup
+import kotlinx.collections.immutable.ImmutableList
+import kotlinx.collections.immutable.toPersistentList
 import java.util.Collections
 import kotlin.math.PI
 import kotlin.math.cos
@@ -38,7 +40,7 @@ import kotlin.math.sin
 @Composable
 fun CompositeAvatar(
     avatarData: AvatarData,
-    heroes: List<AvatarData>,
+    heroes: ImmutableList<AvatarData>,
     modifier: Modifier = Modifier,
     contentDescription: String? = null,
 ) {
@@ -122,27 +124,27 @@ internal fun CompositeAvatarPreview() = ElementThemedPreview {
     ) {
         CompositeAvatar(
             avatarData = mainAvatar,
-            heroes = List(0) { aHeroAvatarData(it) },
+            heroes = List(0) { aHeroAvatarData(it) }.toPersistentList(),
         )
         CompositeAvatar(
             avatarData = mainAvatar,
-            heroes = List(1) { aHeroAvatarData(it) },
+            heroes = List(1) { aHeroAvatarData(it) }.toPersistentList(),
         )
         CompositeAvatar(
             avatarData = mainAvatar,
-            heroes = List(2) { aHeroAvatarData(it) },
+            heroes = List(2) { aHeroAvatarData(it) }.toPersistentList(),
         )
         CompositeAvatar(
             avatarData = mainAvatar,
-            heroes = List(3) { aHeroAvatarData(it) },
+            heroes = List(3) { aHeroAvatarData(it) }.toPersistentList(),
         )
         CompositeAvatar(
             avatarData = mainAvatar,
-            heroes = List(4) { aHeroAvatarData(it) },
+            heroes = List(4) { aHeroAvatarData(it) }.toPersistentList(),
         )
         CompositeAvatar(
             avatarData = mainAvatar,
-            heroes = List(5) { aHeroAvatarData(it) },
+            heroes = List(5) { aHeroAvatarData(it) }.toPersistentList(),
         )
     }
 }