diff --git a/src/types.cpp b/src/types.cpp
index 759f90ca6..66de402f8 100644
--- a/src/types.cpp
+++ b/src/types.cpp
@@ -3094,7 +3094,7 @@ gb_internal bool lookup_subtype_polymorphic_selection(Type *dst, Type *src, Sele
 					return true;
 				}
 			}
-			if ((f->flags & EntityFlag_Using) != 0 && is_type_struct(f->type)) {
+			if ((f->flags & EntityFlags_IsSubtype) != 0 && is_type_struct(f->type)) {
 				String name = lookup_subtype_polymorphic_field(dst, f->type);
 				if (name.len > 0) {
 					array_add(&sel->index, cast(i32)i);
@@ -5030,11 +5030,7 @@ gb_internal isize check_is_assignable_to_using_subtype(Type *src, Type *dst, isi
 				return level+1;
 			}
 		}
-		// Only follow the chain transitively when the field also has `using`, which is
-		// what the backend's lookup_subtype_polymorphic_selection requires (it gates
-		// recursion on EntityFlag_Using). A plain `#subtype`-only field enables a
-		// single-hop conversion but not a two-or-more hop transitive one.
-		if (f->flags & EntityFlag_Using) {
+		if (f->flags & EntityFlags_IsSubtype) {
 			isize nested_level = check_is_assignable_to_using_subtype(f->type, dst, level+1, src_is_ptr, allow_polymorphic);
 			if (nested_level > 0) {
 				return nested_level;