diff --git a/nac3core/src/toplevel/mod.rs b/nac3core/src/toplevel/mod.rs
index fd56508e..c846cc92 100644
--- a/nac3core/src/toplevel/mod.rs
+++ b/nac3core/src/toplevel/mod.rs
@@ -166,6 +166,7 @@ impl TopLevelComposer {
         &mut self,
         ast: ast::Stmt<()>,
         resolver: Option<Arc<Box<dyn SymbolResolver + Send + Sync>>>,
+        mod_path: String,
     ) -> Result<(String, DefinitionId), String> {
         // FIXME: different module same name?
         let defined_class_name = &mut self.defined_class_name;
@@ -176,7 +177,11 @@ impl TopLevelComposer {
                 if self.keyword_list.contains(name) {
                     return Err("cannot use keyword as a class name".into());
                 }
-                if !defined_class_name.insert(name.clone()) {
+                if !defined_class_name.insert({
+                    let mut n = mod_path.clone();
+                    n.push_str(name.as_str());
+                    n
+                }) {
                     return Err("duplicate definition of class".into());
                 }
 
@@ -216,7 +221,11 @@ impl TopLevelComposer {
                         }
                         let global_class_method_name =
                             Self::make_class_method_name(class_name.clone(), method_name);
-                        if !defined_class_method_name.insert(global_class_method_name.clone()) {
+                        if !defined_class_method_name.insert({
+                            let mut n = mod_path.clone();
+                            n.push_str(global_class_method_name.as_str());
+                            n
+                        }) {
                             return Err("duplicate class method definition".into());
                         }
                         if method_name == "__init__" {
@@ -283,7 +292,11 @@ impl TopLevelComposer {
                     return Err("cannot use keyword as a top level function name".into());
                 }
                 let fun_name = name.to_string();
-                if !defined_function_name.insert(name.to_string()) {
+                if !defined_function_name.insert({
+                    let mut n = mod_path.clone();
+                    n.push_str(name.as_str());
+                    n
+                }) {
                     return Err("duplicate top level function define".into());
                 }
 
diff --git a/nac3core/src/toplevel/test.rs b/nac3core/src/toplevel/test.rs
index c56fcd34..48a75acc 100644
--- a/nac3core/src/toplevel/test.rs
+++ b/nac3core/src/toplevel/test.rs
@@ -86,7 +86,7 @@ fn test_simple_register(source: Vec<&str>) {
         let ast = parse_program(s).unwrap();
         let ast = ast[0].clone();
 
-        composer.register_top_level(ast, None).unwrap();
+        composer.register_top_level(ast, None, "__main__".into()).unwrap();
     }
 }
 
@@ -133,7 +133,8 @@ fn test_simple_function_analyze(source: Vec<&str>, tys: Vec<&str>, names: Vec<&s
         let ast = parse_program(s).unwrap();
         let ast = ast[0].clone();
 
-        let (id, def_id) = composer.register_top_level(ast, Some(resolver.clone())).unwrap();
+        let (id, def_id) =
+            composer.register_top_level(ast, Some(resolver.clone()), "__main__".into()).unwrap();
         internal_resolver.add_id_def(id, def_id);
     }
 
@@ -739,6 +740,23 @@ fn test_simple_function_analyze(source: Vec<&str>, tys: Vec<&str>, names: Vec<&s
     vec!["field `a` has already declared in the ancestor classes"];
     "err_incompatible_inheritance_field"
 )]
+#[test_case(
+    vec![
+        indoc! {"
+            class A:
+                def __init__(self):
+                    pass
+        "},
+        indoc! {"
+            class A:
+                a: int32
+                def __init__(self):
+                    pass
+        "}
+    ],
+    vec!["duplicate definition of class"];
+    "class same name"
+)]
 fn test_analyze(source: Vec<&str>, res: Vec<&str>) {
     let print = false;
     let mut composer = TopLevelComposer::new();
@@ -769,7 +787,7 @@ fn test_analyze(source: Vec<&str>, res: Vec<&str>) {
         let ast = ast[0].clone();
 
         let (id, def_id) = {
-            match composer.register_top_level(ast, Some(resolver.clone())) {
+            match composer.register_top_level(ast, Some(resolver.clone()), "__main__".into()) {
                 Ok(x) => x,
                 Err(msg) => {
                     if print {