diff --git a/Tusker/Screens/Compose/ComposeAttachmentsList.swift b/Tusker/Screens/Compose/ComposeAttachmentsList.swift
index 7c79f2fc66..584fc39725 100644
--- a/Tusker/Screens/Compose/ComposeAttachmentsList.swift
+++ b/Tusker/Screens/Compose/ComposeAttachmentsList.swift
@@ -95,8 +95,7 @@ struct ComposeAttachmentsList: View {
         case .pleroma:
             return true
         case .mastodon:
-            // todo: this technically allows invalid image/video combinations
-            return draft.attachments.count < 4
+            return draft.attachments.count < 4 && draft.attachments.allSatisfy { $0.data.type == .image }
         }
     }
     
diff --git a/Tusker/Screens/Compose/ComposeHostingController.swift b/Tusker/Screens/Compose/ComposeHostingController.swift
index 2fca4e6174..d8fe99c5ea 100644
--- a/Tusker/Screens/Compose/ComposeHostingController.swift
+++ b/Tusker/Screens/Compose/ComposeHostingController.swift
@@ -199,7 +199,8 @@ class ComposeHostingController: UIHostingController<ComposeContainerView> {
         case .pleroma:
             return true
         case .mastodon:
-            // todo: this technically allows invalid video/image combinations
+            guard draft.attachments.allSatisfy({ $0.data.type == .image }) else { return false }
+            // todo: if providers are videos, this technically allows invalid video/image combinations
             return itemProviders.count + draft.attachments.count <= 4
         }
     }