diff --git a/packages/beize_shared/lib/bytecode/chunk.dart b/packages/beize_shared/lib/bytecode/chunk.dart
index a290f7b..19ea8f7 100644
--- a/packages/beize_shared/lib/bytecode/chunk.dart
+++ b/packages/beize_shared/lib/bytecode/chunk.dart
@@ -32,7 +32,9 @@ class BeizeChunk {
   }
 
   int codeAt(final int index) => codes[index];
+
   BeizeOpCodes opCodeAt(final int index) => BeizeOpCodes.values[codeAt(index)];
+
   int lineAt(final int index) => lines[index];
 
   BeizeSerializedConstant serialize() => <dynamic>[moduleIndex, codes, lines];
diff --git a/packages/beize_shared/lib/bytecode/constants/program.dart b/packages/beize_shared/lib/bytecode/constants/program.dart
index 57ce2f5..67975bb 100644
--- a/packages/beize_shared/lib/bytecode/constants/program.dart
+++ b/packages/beize_shared/lib/bytecode/constants/program.dart
@@ -3,7 +3,6 @@ import 'function.dart';
 
 class BeizeProgramConstant {
   const BeizeProgramConstant({
-    // required this.moduleNames,
     required this.modules,
     required this.constants,
   });
@@ -13,13 +12,6 @@ class BeizeProgramConstant {
   ) =>
       BeizeProgramConstant(
         modules: (serialized[0] as List<dynamic>).cast<int>(),
-        // modules: (serialized[1] as List<dynamic>)
-        //     .map(
-        //       (final dynamic x) => BeizeFunctionConstant.deserialize(
-        //         x as BeizeSerializedConstant,
-        //       ),
-        //     )
-        //     .toList(),
         constants: (serialized[1] as List<dynamic>).map((final dynamic x) {
           if (x is List<dynamic>) {
             return BeizeFunctionConstant.deserialize(x);
@@ -28,11 +20,14 @@ class BeizeProgramConstant {
         }).toList(),
       );
 
-  // final List<String> moduleNames;
   final List<int> modules;
   final List<BeizeConstant> constants;
 
-  int moduleAt(final int index) => modules[index];
+  String moduleNameAt(final int index) => constantAt(modules[index]) as String;
+
+  BeizeFunctionConstant moduleFunctionAt(final int index) =>
+      constantAt(modules[index + 1]) as BeizeFunctionConstant;
+
   BeizeConstant constantAt(final int index) => constants[index];
 
   BeizeSerializedConstant serialize() => <dynamic>[
diff --git a/packages/beize_vm/lib/vm/call_frame.dart b/packages/beize_vm/lib/vm/call_frame.dart
index 8d25cc4..700b05b 100644
--- a/packages/beize_vm/lib/vm/call_frame.dart
+++ b/packages/beize_vm/lib/vm/call_frame.dart
@@ -110,8 +110,8 @@ class BeizeCallFrame {
       vm.program.constantAt(function.chunk.codeAt(index));
 
   String toStackTraceLine(final int depth) {
-    final int nameIndex = vm.program.modules[function.chunk.moduleIndex];
-    final String moduleName = vm.program.constantAt(nameIndex) as String;
+    final String moduleName =
+        vm.program.moduleNameAt(function.chunk.moduleIndex);
     final int line = function.chunk.lineAt(sip);
     return '#$depth   $moduleName at line $line';
   }
diff --git a/packages/beize_vm/lib/vm/interpreter.dart b/packages/beize_vm/lib/vm/interpreter.dart
index 8d06764..f0dfcb8 100644
--- a/packages/beize_vm/lib/vm/interpreter.dart
+++ b/packages/beize_vm/lib/vm/interpreter.dart
@@ -497,16 +497,21 @@ class BeizeInterpreter {
       case BeizeOpCodes.opImport:
         final int moduleIndex = chunk.codeAt(frame.ip);
         final int asIndex = chunk.codeAt(frame.ip + 1);
-        final String name = frame.readConstantAt(asIndex) as String;
+        final String name = frame.vm.program.constantAt(asIndex) as String;
         frame.ip += 2;
-        final BeizePreparedModule module = frame.vm.prepareModule(
-          moduleIndex,
-          isEntrypoint: false,
-        );
-        namespace.declare(name, module.value);
-        final BeizeInterpreterResult result = frame.vm.loadModule(module);
-        if (result.isFailure) {
-          return handleException(result.error);
+        final BeizeModuleValue? pValue = frame.vm.lookupModule(moduleIndex);
+        if (pValue != null) {
+          namespace.declare(name, pValue);
+        } else {
+          final BeizePreparedModule module = frame.vm.prepareModule(
+            moduleIndex,
+            isEntrypoint: false,
+          );
+          namespace.declare(name, module.value);
+          final BeizeInterpreterResult result = frame.vm.loadModule(module);
+          if (result.isFailure) {
+            return handleException(result.error);
+          }
         }
         break;
 
diff --git a/packages/beize_vm/lib/vm/vm.dart b/packages/beize_vm/lib/vm/vm.dart
index d17d4db..f15f441 100644
--- a/packages/beize_vm/lib/vm/vm.dart
+++ b/packages/beize_vm/lib/vm/vm.dart
@@ -37,7 +37,7 @@ class BeizeVM {
   final BeizeVMOptions options;
 
   final BeizeNamespace globalNamespace = BeizeNamespace.withNatives();
-  final Map<String, BeizeModuleValue> modules = <String, BeizeModuleValue>{};
+  final Map<int, BeizeModuleValue> modules = <int, BeizeModuleValue>{};
   late final BeizeCallFrame topFrame;
 
   Future<void> run() async {
@@ -51,22 +51,24 @@ class BeizeVM {
     }
   }
 
+  BeizeModuleValue? lookupModule(final int moduleIndex) => modules[moduleIndex];
+
   BeizePreparedModule prepareModule(
     final int moduleIndex, {
     required final bool isEntrypoint,
   }) {
-    final int nameIndex = program.moduleAt(moduleIndex);
-    final String moduleName = program.constantAt(nameIndex) as String;
     final BeizeNamespace namespace = globalNamespace.enclosed;
     final BeizeModuleValue value = BeizeModuleValue(namespace);
-    modules[moduleName] = value;
+    modules[moduleIndex] = value;
     final BeizeCallFrame frame = BeizeCallFrame(
       vm: this,
-      function: program.constantAt(nameIndex + 1) as BeizeFunctionConstant,
+      function: program.moduleFunctionAt(moduleIndex),
       namespace: namespace,
       parent: !isEntrypoint ? topFrame : null,
     );
-    if (isEntrypoint) topFrame = frame;
+    if (isEntrypoint) {
+      topFrame = frame;
+    }
     return BeizePreparedModule(
       moduleIndex: moduleIndex,
       frame: frame,