diff --git a/main/src/ui/unified_window.vala b/main/src/ui/unified_window.vala
index 8338573e..44107fb3 100644
--- a/main/src/ui/unified_window.vala
+++ b/main/src/ui/unified_window.vala
@@ -28,10 +28,11 @@ public class UnifiedWindow : Gtk.Window {
             return Util.use_csd() ? conversation_titlebar_csd.subtitle : conversation_titlebar.subtitle;
         }
         set {
+            string? new_subtitle = value == null ? null : (new Regex("\\s+")).replace_literal(value, -1, 0, " ");
             if (Util.use_csd()) {
-                conversation_titlebar_csd.subtitle = value;
+                conversation_titlebar_csd.subtitle = new_subtitle;
             } else {
-                conversation_titlebar.subtitle = value;
+                conversation_titlebar.subtitle = new_subtitle;
             }
         }
     }
diff --git a/main/src/ui/unified_window_controller.vala b/main/src/ui/unified_window_controller.vala
index dce5b39f..bef6b7dc 100644
--- a/main/src/ui/unified_window_controller.vala
+++ b/main/src/ui/unified_window_controller.vala
@@ -147,7 +147,7 @@ public class UnifiedWindowController : Object {
     }
 
     private void update_conversation_topic(string? subtitle = null) {
-        if (conversation_topic != null) {
+        if (subtitle != null) {
             conversation_topic = subtitle;
         } else if (conversation.type_ == Conversation.Type.GROUPCHAT) {
             string subject = stream_interactor.get_module(MucManager.IDENTITY).get_groupchat_subject(conversation.counterpart, conversation.account);