diff --git a/ets2panda/checker/ETSAnalyzer.cpp b/ets2panda/checker/ETSAnalyzer.cpp
index 3fe590ae199f220822b23cb74cc52f9c48905d17..6c13296f648f7e4399df5fa58ce59cdaf81d0c28 100644
--- a/ets2panda/checker/ETSAnalyzer.cpp
+++ b/ets2panda/checker/ETSAnalyzer.cpp
@@ -2004,7 +2004,12 @@ checker::Type *ETSAnalyzer::CheckDynamic(ir::ObjectExpression *expr) const
 
 static bool ValidatePreferredType(ETSChecker *checker, ir::ObjectExpression *expr)
 {
-    auto preferredType = expr->PreferredType();
+    auto preferredType = expr->PreferredType()->MaybeBaseTypeOfGradualType();
+    if (preferredType == nullptr) {
+        checker->LogError(diagnostic::CLASS_COMPOSITE_UNKNOWN_TYPE, {}, expr->Start());
+        return false;
+    }
+
     if (preferredType->IsTypeError()) {
         //  Don't need to duplicate error message for a single error.
         return false;
diff --git a/ets2panda/compiler/lowering/ets/interfacePropertyDeclarations.cpp b/ets2panda/compiler/lowering/ets/interfacePropertyDeclarations.cpp
index 9ffb2732ec79529dfbc8f6fae64ab9a5ed0e3395..66fb67ba663d0820b68437c86063e8909f419750 100644
--- a/ets2panda/compiler/lowering/ets/interfacePropertyDeclarations.cpp
+++ b/ets2panda/compiler/lowering/ets/interfacePropertyDeclarations.cpp
@@ -125,7 +125,8 @@ ir::MethodDefinition *InterfacePropertyDeclarationsPhase::GenerateGetterOrSetter
         ctx->Allocator(), ir::ScriptFunction::ScriptFunctionData {
                               nullptr, std::move(signature),  // CC-OFF(G.FMT.02) project code style
                               // CC-OFFNXT(G.FMT.02) project code style
-                              isSetter ? ir::ScriptFunctionFlags::SETTER : ir::ScriptFunctionFlags::GETTER, flags});
+                              isSetter ? ir::ScriptFunctionFlags::SETTER : ir::ScriptFunctionFlags::GETTER, flags,
+                              classScope->Node()->AsTSInterfaceDeclaration()->Language()});
 
     func->SetRange(field->Range());
     func->SetScope(functionScope);
diff --git a/ets2panda/compiler/lowering/ets/unboxLowering.cpp b/ets2panda/compiler/lowering/ets/unboxLowering.cpp
index 0e5299b8229ce42fd61f03c60511f0142ff83851..ef0704c10e907b0bdfc4545435a4420914901f9c 100644
--- a/ets2panda/compiler/lowering/ets/unboxLowering.cpp
+++ b/ets2panda/compiler/lowering/ets/unboxLowering.cpp
@@ -268,6 +268,11 @@ static void NormalizeAllTypes(UnboxContext *uctx, ir::AstNode *ast)
 
 static void HandleScriptFunctionHeader(UnboxContext *uctx, ir::ScriptFunction *func)
 {
+    // dynamic function does not need to unbox
+    if (func->Language() == Language::Id::JS) {
+        return;
+    }
+
     auto *sig = func->Signature();
     if (sig == nullptr) {
         return;