diff --git a/xalia/AtSpi2/AccessibleProvider.cs b/xalia/AtSpi2/AccessibleProvider.cs
index 9015022..2aa85f3 100644
--- a/xalia/AtSpi2/AccessibleProvider.cs
+++ b/xalia/AtSpi2/AccessibleProvider.cs
@@ -912,9 +912,10 @@ public override bool WatchProperty(UiDomElement element, GudlExpression expressi
                     case "spi_supported":
                         if (!fetching_supported)
                         {
-                            fetching_supported = true;
-                            wait_for_supported_task = FetchSupported();
-                            Utils.RunTask(wait_for_supported_task);
+                            // Somehow, FetchSupported can complete without waiting, which
+                            // would modify the providers list while it's being iterated to
+                            // call WatchProperty, so delay it to prevent that.
+                            Utils.RunIdle(DoFetchSupported);
                         }
                         break;
                     case "spi_application":
@@ -934,6 +935,16 @@ public override bool WatchProperty(UiDomElement element, GudlExpression expressi
             return false;
         }
 
+        private void DoFetchSupported()
+        {
+            if (!fetching_supported)
+            {
+                fetching_supported = true;
+                wait_for_supported_task = FetchSupported();
+                Utils.RunTask(wait_for_supported_task);
+            }
+        }
+
         private async Task FetchAttributes()
         {
             var old_change_count = attributes_change_count;