diff --git a/tl.lua b/tl.lua
index afae1e50..26fc2d18 100644
--- a/tl.lua
+++ b/tl.lua
@@ -7667,7 +7667,9 @@ do
             end
          elseif t.typename == "self" then
             assert(copy.typename == "self")
-            copy.display_type, same = resolve(t.display_type, same)
+            if t.display_type ~= nil then
+               copy.display_type, same = resolve(t.display_type, same)
+            end
          end
 
          copy.typeid = same and t.typeid or new_typeid()
diff --git a/tl.tl b/tl.tl
index d0d6e262..54db870c 100644
--- a/tl.tl
+++ b/tl.tl
@@ -7667,7 +7667,9 @@ do
             end
          elseif t is SelfType then
             assert(copy is SelfType)
-            copy.display_type, same = resolve(t.display_type, same)
+            if t.display_type ~= nil then
+               copy.display_type, same = resolve(t.display_type, same)
+            end
          end
 
          copy.typeid = same and t.typeid or new_typeid()