diff --git a/TestSuite/errors/err0239.pas b/TestSuite/errors/err0239.pas
new file mode 100644
index 000000000..2775aef42
--- /dev/null
+++ b/TestSuite/errors/err0239.pas
@@ -0,0 +1,7 @@
+type
+  I1 = interface 
+  end;
+
+begin
+  (I1(System.Math.Sin)); 
+end.
\ No newline at end of file
diff --git a/TreeConverter/TreeConversion/convertion_data_and_alghoritms.cs b/TreeConverter/TreeConversion/convertion_data_and_alghoritms.cs
index c7cd4a357..97f374184 100644
--- a/TreeConverter/TreeConversion/convertion_data_and_alghoritms.cs
+++ b/TreeConverter/TreeConversion/convertion_data_and_alghoritms.cs
@@ -681,7 +681,7 @@ namespace PascalABCCompiler.TreeConverter
                 return ret;
             }
 
-            if ((type_table.is_derived(from.type, to)) || (type_table.is_derived(to, from.type)) || from.type.IsInterface || to.IsInterface)
+            if ((type_table.is_derived(from.type, to)) || (type_table.is_derived(to, from.type)) || from.type.IsInterface || to.IsInterface && !(from.type is delegated_methods))
             {
                 if (from.type.IsSealed && to.IsInterface && !from.type.ImplementingInterfaces.Contains(to) ||
                     from.type.IsInterface && to.IsSealed && !to.ImplementingInterfaces.Contains(from.type))