diff --git a/py2wasm/python.py b/py2wasm/python.py
index 8e5876c..41f7978 100644
--- a/py2wasm/python.py
+++ b/py2wasm/python.py
@@ -12,7 +12,7 @@ from . import wasm
 
 StatementGenerator = Generator[wasm.Statement, None, None]
 
-WLocals = Dict[str, str]
+WLocals = Dict[str, wasm.OurType]
 
 class Visitor:
     """
@@ -21,6 +21,29 @@ class Visitor:
     Since we need to visit the whole tree, there's no point in subclassing
     the buildin visitor
     """
+
+    def __init__(self) -> None:
+        self._type_map: WLocals = {
+            'None': wasm.OurTypeNone(),
+            'bool': wasm.OurTypeBool(),
+            'i32': wasm.OurTypeInt32(),
+            'i64': wasm.OurTypeInt64(),
+            'f32': wasm.OurTypeFloat32(),
+            'f64': wasm.OurTypeFloat64(),
+        }
+
+    def _get_type(self, name: Union[None, str, ast.expr]) -> wasm.OurType:
+        if name is None:
+            name = 'None'
+
+        if isinstance(name, ast.expr):
+            if isinstance(name, ast.Name):
+                name = name.id
+            else:
+                raise NotImplementedError(f'_get_type(ast.{type(name).__name__})')
+
+        return self._type_map[name]
+
     def visit_Module(self, node: ast.Module) -> wasm.Module:
         """
         Visits a Python module, which results in a wasm Module
@@ -33,12 +56,12 @@ class Visitor:
             '___new_reference___',
             False,
             [
-                ('alloc_size', 'i32'),
+                ('alloc_size', self._get_type('i32')),
             ],
             [
-                ('result', 'i32'),
+                ('result', self._get_type('i32')),
             ],
-            'i32',
+            self._get_type('i32'),
             [
                 wasm.Statement('i32.const', '0'),
                 wasm.Statement('i32.const', '0'),
@@ -69,7 +92,7 @@ class Visitor:
 
             if isinstance(stmt, ast.ClassDef):
                 wclass = self.pre_visit_ClassDef(module, stmt)
-                module.classes.append(wclass)
+                self._type_map[wclass.name] = wclass
                 continue
 
             # No other pre visits to do
@@ -122,13 +145,13 @@ class Visitor:
 
                 assert not call.keywords
 
-                mod, name, intname = _parse_import_decorator(node.name, call.args)
+                mod, name, intname = self._parse_import_decorator(node.name, call.args)
 
-                return wasm.Import(mod, name, intname, _parse_import_args(node.args))
+                return wasm.Import(mod, name, intname, self._parse_import_args(node.args))
             else:
                 raise NotImplementedError
 
-        result = None if node.returns is None else _parse_annotation(node.returns)
+        result = None if node.returns is None else self._get_type(node.returns)
 
         assert not node.args.vararg
         assert not node.args.kwonlyargs
@@ -136,23 +159,12 @@ class Visitor:
         assert not node.args.kwarg
         assert not node.args.defaults
 
-        class_lookup = {
-            x.name: x
-            for x in module.classes
-        }
-
-        params = []
+        params: List[wasm.Param] = []
         for arg in [*node.args.posonlyargs, *node.args.args]:
-            if not isinstance(arg.annotation, ast.Name):
-                raise NotImplementedError
+            params.append((arg.arg, self._get_type(arg.annotation), ))
 
-            if arg.annotation.id in class_lookup:
-                params.append((arg.arg, 'i32', ))
-            else:
-                params.append((arg.arg, _parse_annotation(arg.annotation), ))
-
-        locals_ = [
-            ('___new_reference___addr', 'i32'), # For the ___new_reference__ method
+        locals_: List[wasm.Param] = [
+            ('___new_reference___addr', self._get_type('i32')), # For the ___new_reference__ method
         ]
 
         return wasm.Function(node.name, exported, params, locals_, result, [])
@@ -180,7 +192,7 @@ class Visitor:
             self,
             module: wasm.Module,
             node: ast.ClassDef,
-        ) -> wasm.Class:
+        ) -> wasm.OurTypeClass:
         """
         TODO: Document this
         """
@@ -200,7 +212,7 @@ class Visitor:
                 raise NotImplementedError
 
             if not isinstance(stmt.annotation, ast.Name):
-                raise NotImplementedError
+                raise NotImplementedError('Cannot recurse classes yet')
 
             if stmt.annotation.id != 'i32':
                 raise NotImplementedError
@@ -217,13 +229,13 @@ class Visitor:
                 default = wasm.Constant(stmt.value.value)
 
             member = wasm.ClassMember(
-                stmt.target.id, stmt.annotation.id, offset, default
+                stmt.target.id, self._get_type(stmt.annotation), offset, default
             )
 
             members.append(member)
-            offset += member.alloc_size()
+            offset += member.type.alloc_size()
 
-        return wasm.Class(node.name, members)
+        return wasm.OurTypeClass(node.name, members)
 
     def visit_stmt(
             self,
@@ -241,7 +253,7 @@ class Visitor:
         if isinstance(stmt, ast.Expr):
             assert isinstance(stmt.value, ast.Call)
 
-            return self.visit_Call(module, wlocals, "None", stmt.value)
+            return self.visit_Call(module, wlocals, self._get_type('None'), stmt.value)
 
         if isinstance(stmt, ast.If):
             return self.visit_If(module, func, wlocals, stmt)
@@ -261,7 +273,7 @@ class Visitor:
 
         assert stmt.value is not None
 
-        return_type = _parse_annotation(func.returns)
+        return_type = self._get_type(func.returns)
 
         yield from self.visit_expr(module, wlocals, return_type, stmt.value)
         yield wasm.Statement('return')
@@ -279,7 +291,7 @@ class Visitor:
         yield from self.visit_expr(
             module,
             wlocals,
-            'bool',
+            self._get_type('bool'),
             stmt.test,
         )
 
@@ -299,7 +311,7 @@ class Visitor:
             self,
             module: wasm.Module,
             wlocals: WLocals,
-            exp_type: str,
+            exp_type: wasm.OurType,
             node: ast.expr,
         ) -> StatementGenerator:
         """
@@ -332,7 +344,7 @@ class Visitor:
             self,
             module: wasm.Module,
             wlocals: WLocals,
-            exp_type: str,
+            exp_type: wasm.OurType,
             node: ast.UnaryOp,
         ) -> StatementGenerator:
         """
@@ -356,7 +368,7 @@ class Visitor:
             self,
             module: wasm.Module,
             wlocals: WLocals,
-            exp_type: str,
+            exp_type: wasm.OurType,
             node: ast.BinOp,
         ) -> StatementGenerator:
         """
@@ -366,11 +378,11 @@ class Visitor:
         yield from self.visit_expr(module, wlocals, exp_type, node.right)
 
         if isinstance(node.op, ast.Add):
-            yield wasm.Statement('{}.add'.format(exp_type))
+            yield wasm.Statement('{}.add'.format(exp_type.to_wasm()))
             return
 
         if isinstance(node.op, ast.Sub):
-            yield wasm.Statement('{}.sub'.format(exp_type))
+            yield wasm.Statement('{}.sub'.format(exp_type.to_wasm()))
             return
 
         raise NotImplementedError(node.op)
@@ -379,19 +391,19 @@ class Visitor:
             self,
             module: wasm.Module,
             wlocals: WLocals,
-            exp_type: str,
+            exp_type: wasm.OurType,
             node: ast.Compare,
         ) -> StatementGenerator:
         """
         Visits a Compare node as (part of) an expression
         """
-        assert 'bool' == exp_type
+        assert isinstance(exp_type, wasm.OurTypeBool)
 
         if 1 != len(node.ops) or 1 != len(node.comparators):
             raise NotImplementedError
 
-        yield from self.visit_expr(module, wlocals, 'i32', node.left)
-        yield from self.visit_expr(module, wlocals, 'i32', node.comparators[0])
+        yield from self.visit_expr(module, wlocals, self._get_type('i32'), node.left)
+        yield from self.visit_expr(module, wlocals, self._get_type('i32'), node.comparators[0])
 
         if isinstance(node.ops[0], ast.Lt):
             yield wasm.Statement('i32.lt_s')
@@ -411,7 +423,7 @@ class Visitor:
             self,
             module: wasm.Module,
             wlocals: WLocals,
-            exp_type: str,
+            exp_type: wasm.OurType,
             node: ast.Call,
         ) -> StatementGenerator:
         """
@@ -422,11 +434,15 @@ class Visitor:
 
         called_name = node.func.id
 
-        search_list: List[Union[wasm.Function, wasm.Import, wasm.Class]]
+        if called_name in self._type_map:
+            klass = self._type_map[called_name]
+            if isinstance(klass, wasm.OurTypeClass):
+                return self.visit_Call_class(module, wlocals, exp_type, node, klass)
+
+        search_list: List[Union[wasm.Function, wasm.Import]]
         search_list = [
             *module.functions,
             *module.imports,
-            *module.classes,
         ]
 
         called_func_list = [
@@ -438,18 +454,15 @@ class Visitor:
         assert 1 == len(called_func_list), \
             'Could not find function {}'.format(node.func.id)
 
-        if isinstance(called_func_list[0], wasm.Class):
-            return self.visit_Call_class(module, wlocals, exp_type, node, called_func_list[0])
-
         return self.visit_Call_func(module, wlocals, exp_type, node, called_func_list[0])
 
     def visit_Call_class(
             self,
             module: wasm.Module,
             wlocals: WLocals,
-            exp_type: str,
+            exp_type: wasm.OurType,
             node: ast.Call,
-            cls: wasm.Class,
+            cls: wasm.OurTypeClass,
         ) -> StatementGenerator:
         """
         Visits a Call node as (part of) an expression
@@ -469,8 +482,8 @@ class Visitor:
                 raise NotImplementedError
 
             yield wasm.Statement('local.get', '$___new_reference___addr')
-            yield wasm.Statement(f'{member.type}.const', str(arg.value))
-            yield wasm.Statement(f'{member.type}.store', 'offset=' + str(member.offset))
+            yield wasm.Statement(f'{member.type.to_wasm()}.const', str(arg.value))
+            yield wasm.Statement(f'{member.type.to_wasm()}.store', 'offset=' + str(member.offset))
 
         yield wasm.Statement('local.get', '$___new_reference___addr')
 
@@ -478,7 +491,7 @@ class Visitor:
             self,
             module: wasm.Module,
             wlocals: WLocals,
-            exp_type: str,
+            exp_type: wasm.OurType,
             node: ast.Call,
             func: Union[wasm.Function, wasm.Import],
         ) -> StatementGenerator:
@@ -491,7 +504,7 @@ class Visitor:
         called_params = func.params
         called_result = func.result
 
-        assert exp_type == called_result
+        assert exp_type == called_result, 'Function does not match expected type'
 
         assert len(called_params) == len(node.args), \
             '{}:{} Function {} requires {} arguments, but {} are supplied'.format(
@@ -507,32 +520,32 @@ class Visitor:
             '${}'.format(called_name),
         )
 
-    def visit_Constant(self, exp_type: str, node: ast.Constant) -> StatementGenerator:
+    def visit_Constant(self, exp_type: wasm.OurType, node: ast.Constant) -> StatementGenerator:
         """
         Visits a Constant node as (part of) an expression
         """
-        if 'i32' == exp_type:
+        if isinstance(exp_type, wasm.OurTypeInt32):
             assert isinstance(node.value, int)
             assert -2147483648 <= node.value <= 2147483647
 
             yield wasm.Statement('i32.const', str(node.value))
             return
 
-        if 'i64' == exp_type:
+        if isinstance(exp_type, wasm.OurTypeInt64):
             assert isinstance(node.value, int)
             assert -9223372036854775808 <= node.value <= 9223372036854775807
 
             yield wasm.Statement('i64.const', str(node.value))
             return
 
-        if 'f32' == exp_type:
+        if isinstance(exp_type, wasm.OurTypeFloat32):
             assert isinstance(node.value, float)
             # TODO: Size check?
 
             yield wasm.Statement('f32.const', node.value.hex())
             return
 
-        if 'f64' == exp_type:
+        if isinstance(exp_type, wasm.OurTypeFloat64):
             assert isinstance(node.value, float)
             # TODO: Size check?
 
@@ -545,27 +558,21 @@ class Visitor:
             self,
             module: wasm.Module,
             wlocals: WLocals,
-            exp_type: str,
+            exp_type: wasm.OurType,
             node: ast.Attribute,
         ) -> StatementGenerator:
         """
         Visits an Attribute node as (part of) an expression
         """
-
         if not isinstance(node.value, ast.Name):
             raise NotImplementedError
 
         if not isinstance(node.ctx, ast.Load):
             raise NotImplementedError
 
-        cls_list = [
-            x
-            for x in module.classes
-            if x.name == 'Rectangle' # TODO: STUB, since we can't acces the type properly
-        ]
+        cls = wlocals[node.value.id]
 
-        assert len(cls_list) == 1
-        cls = cls_list[0]
+        assert isinstance(cls, wasm.OurTypeClass), f'Cannot take property of {cls}'
 
         member_list = [
             x
@@ -577,79 +584,71 @@ class Visitor:
         member = member_list[0]
 
         yield wasm.Statement('local.get', '$' + node.value.id)
-        yield wasm.Statement(exp_type + '.load', 'offset=' + str(member.offset))
+        yield wasm.Statement(exp_type.to_wasm() + '.load', 'offset=' + str(member.offset))
 
-    def visit_Name(self, wlocals: WLocals, exp_type: str, node: ast.Name) -> StatementGenerator:
+    def visit_Name(self, wlocals: WLocals, exp_type: wasm.OurType, node: ast.Name) -> StatementGenerator:
         """
         Visits a Name node as (part of) an expression
         """
         assert node.id in wlocals
 
-        if exp_type == 'i64' and wlocals[node.id] == 'i32':
+        if (isinstance(exp_type, wasm.OurTypeInt64)
+            and isinstance(wlocals[node.id], wasm.OurTypeInt32)):
             yield wasm.Statement('local.get', '${}'.format(node.id))
             yield wasm.Statement('i64.extend_i32_s')
             return
 
-        if exp_type == 'f64' and wlocals[node.id] == 'f32':
+        if (isinstance(exp_type, wasm.OurTypeFloat64)
+            and isinstance(wlocals[node.id], wasm.OurTypeFloat32)):
             yield wasm.Statement('local.get', '${}'.format(node.id))
             yield wasm.Statement('f64.promote_f32')
             return
 
-        assert exp_type == wlocals[node.id]
+        assert exp_type == wlocals[node.id], (exp_type, wlocals[node.id], )
         yield wasm.Statement(
             'local.get',
             '${}'.format(node.id),
         )
 
-def _parse_import_decorator(func_name: str, args: List[ast.expr]) -> Tuple[str, str, str]:
-    """
-    Parses an @import decorator
-    """
+    def _parse_import_decorator(self, func_name: str, args: List[ast.expr]) -> Tuple[str, str, str]:
+        """
+        Parses an @import decorator
+        """
 
-    assert 0 < len(args) < 3
-    str_args = [
-        arg.value
-        for arg in args
-        if isinstance(arg, ast.Constant)
-        and isinstance(arg.value, str)
-    ]
-    assert len(str_args) == len(args)
+        assert 0 < len(args) < 3
+        str_args = [
+            arg.value
+            for arg in args
+            if isinstance(arg, ast.Constant)
+            and isinstance(arg.value, str)
+        ]
+        assert len(str_args) == len(args)
 
-    module = str_args.pop(0)
-    if str_args:
-        name = str_args.pop(0)
-    else:
-        name = func_name
+        module = str_args.pop(0)
+        if str_args:
+            name = str_args.pop(0)
+        else:
+            name = func_name
 
-    return module, name, func_name
+        return module, name, func_name
 
-def _parse_import_args(args: ast.arguments) -> List[Tuple[str, str]]:
-    """
-    Parses the arguments for an @imported method
-    """
+    def _parse_import_args(self, args: ast.arguments) -> List[wasm.Param]:
+        """
+        Parses the arguments for an @imported method
+        """
 
-    assert not args.vararg
-    assert not args.kwonlyargs
-    assert not args.kw_defaults
-    assert not args.kwarg
-    assert not args.defaults # Maybe support this later on
+        assert not args.vararg
+        assert not args.kwonlyargs
+        assert not args.kw_defaults
+        assert not args.kwarg
+        assert not args.defaults # Maybe support this later on
 
-    arg_list = [
-        *args.posonlyargs,
-        *args.args,
-    ]
+        arg_list = [
+            *args.posonlyargs,
+            *args.args,
+        ]
 
-    return [
-        (arg.arg, _parse_annotation(arg.annotation))
-        for arg in arg_list
-    ]
-
-def _parse_annotation(ann: Optional[ast.expr]) -> str:
-    """
-    Parses a typing annotation
-    """
-    assert ann is not None, 'Web Assembly requires type annotations'
-    assert isinstance(ann, ast.Name)
-    result = ann.id
-    assert result in ['i32', 'i64', 'f32', 'f64'], result
-    return result
+        return [
+            (arg.arg, self._get_type(arg.annotation))
+            for arg in arg_list
+        ]
diff --git a/py2wasm/wasm.py b/py2wasm/wasm.py
index b025617..1939301 100644
--- a/py2wasm/wasm.py
+++ b/py2wasm/wasm.py
@@ -2,9 +2,90 @@
 Python classes for storing the representation of Web Assembly code
 """
 
-from typing import Iterable, List, Optional, Tuple, Union
+from typing import Any, Iterable, List, Optional, Tuple, Union
 
-Param = Tuple[str, str]
+###
+### This part is more intermediate code
+###
+
+class OurType:
+    def to_wasm(self) -> str:
+        raise NotImplementedError
+
+    def alloc_size(self) -> int:
+        raise NotImplementedError
+
+class OurTypeNone(OurType):
+    pass
+
+class OurTypeBool(OurType):
+    pass
+
+class OurTypeInt32(OurType):
+    def to_wasm(self) -> str:
+        return 'i32'
+
+    def alloc_size(self) -> int:
+        return 4
+
+class OurTypeInt64(OurType):
+    def to_wasm(self) -> str:
+        return 'i64'
+
+    def alloc_size(self) -> int:
+        return 8
+
+class OurTypeFloat32(OurType):
+    def to_wasm(self) -> str:
+        return 'f32'
+
+    def alloc_size(self) -> int:
+        return 4
+
+class OurTypeFloat64(OurType):
+    def to_wasm(self) -> str:
+        return 'f64'
+
+    def alloc_size(self) -> int:
+        return 8
+
+class Constant:
+    """
+    TODO
+    """
+    def __init__(self, value: Union[None, bool, int, float]) -> None:
+        self.value = value
+
+class ClassMember:
+    """
+    Represents a class member
+    """
+    def __init__(self, name: str, type_: OurType, offset: int, default: Optional[Constant]) -> None:
+        self.name = name
+        self.type = type_
+        self.offset = offset
+        self.default = default
+
+class OurTypeClass(OurType):
+    """
+    Represents a class
+    """
+    def __init__(self, name: str, members: List[ClassMember]) -> None:
+        self.name = name
+        self.members = members
+
+    def to_wasm(self) -> str:
+        return 'i32' # WASM uses 32 bit pointers
+
+    def alloc_size(self) -> int:
+        return sum(x.type.alloc_size() for x in self.members)
+
+
+Param = Tuple[str, OurType]
+
+###
+## This part is more actual web assembly
+###
 
 class Import:
     """
@@ -62,7 +143,7 @@ class Function:
             exported: bool,
             params: Iterable[Param],
             locals_: Iterable[Param],
-            result: Optional[str],
+            result: Optional[OurType],
             statements: Iterable[Statement],
         ) -> None:
         self.name = name
@@ -79,55 +160,19 @@ class Function:
         header = ('(export "{}")' if self.exported else '${}').format(self.name)
 
         for nam, typ in self.params:
-            header += f' (param ${nam} {typ})'
+            header += f' (param ${nam} {typ.to_wasm()})'
 
         if self.result:
-            header += f' (result {self.result})'
+            header += f' (result {self.result.to_wasm()})'
 
         for nam, typ in self.locals:
-            header += f' (local ${nam} {typ})'
+            header += f' (local ${nam} {typ.to_wasm()})'
 
         return '(func {}\n    {}\n    )'.format(
             header,
             '\n    '.join(x.generate() for x in self.statements),
         )
 
-class Constant:
-    """
-    TODO
-    """
-    def __init__(self, value: Union[None, bool, int, float]) -> None:
-        self.value = value
-
-class ClassMember:
-    """
-    Represents a Web Assembly class member
-    """
-    def __init__(self, name: str, type_: str, offset: int, default: Optional[Constant]) -> None:
-        self.name = name
-        self.type = type_
-        self.offset = offset
-        self.default = default
-
-    def alloc_size(self) -> int:
-        SIZE_MAP = {
-            'i32': 4,
-            'i64': 4,
-        }
-
-        return SIZE_MAP[self.type]
-
-class Class:
-    """
-    Represents a Web Assembly class
-    """
-    def __init__(self, name: str, members: List[ClassMember]) -> None:
-        self.name = name
-        self.members = members
-
-    def alloc_size(self) -> int:
-        return sum(x.alloc_size() for x in self.members)
-
 class Module:
     """
     Represents a Web Assembly module
@@ -135,7 +180,6 @@ class Module:
     def __init__(self) -> None:
         self.imports: List[Import] = []
         self.functions: List[Function] = []
-        self.classes: List[Class] = []
 
     def generate(self) -> str:
         """
diff --git a/tests/integration/test_simple.py b/tests/integration/test_simple.py
index ca70345..dca3291 100644
--- a/tests/integration/test_simple.py
+++ b/tests/integration/test_simple.py
@@ -251,6 +251,26 @@ def testEntry() -> i32:
     assert 8947 == result.returned_value
     assert [] == result.log_int32_list
 
+@pytest.mark.integration_test
+def test_struct_0():
+    code_py = """
+
+class CheckedValue:
+    value: i32
+
+@exported
+def testEntry() -> i32:
+    return helper(CheckedValue(2345))
+
+def helper(cv: CheckedValue) -> i32:
+    return cv.value
+"""
+
+    result = Suite(code_py, 'test_call').run_code()
+
+    assert 2345 == result.returned_value
+    assert [] == result.log_int32_list
+
 @pytest.mark.integration_test
 def test_struct_1():
     code_py = """