diff --git a/phasm/ourlang.py b/phasm/ourlang.py
index 4200f2f..696cf9e 100644
--- a/phasm/ourlang.py
+++ b/phasm/ourlang.py
@@ -224,22 +224,20 @@ class FunctionParam:
     """
     A parameter for a Function
     """
-    __slots__ = ('name', 'type3', 'type_str', )
+    __slots__ = ('name', 'type3', )
 
     name: str
-    type3: Type3
-    type_str: str
+    type3: Type3OrPlaceholder
 
-    def __init__(self, name: str, type3: Type3) -> None:
+    def __init__(self, name: str, type3: Optional[Type3]) -> None:
         self.name = name
-        self.type3 = type3
-        self.type_str = type3.name
+        self.type3 = PlaceholderForType([self]) if type3 is None else type3
 
 class Function:
     """
     A function processes input and produces output
     """
-    __slots__ = ('name', 'lineno', 'exported', 'imported', 'statements', 'returns_type3', 'returns_str', 'posonlyargs', )
+    __slots__ = ('name', 'lineno', 'exported', 'imported', 'statements', 'returns_type3', 'posonlyargs', )
 
     name: str
     lineno: int
@@ -247,7 +245,6 @@ class Function:
     imported: bool
     statements: List[Statement]
     returns_type3: Type3
-    returns_str: str
     posonlyargs: List[FunctionParam]
 
     def __init__(self, name: str, lineno: int) -> None:
@@ -256,8 +253,7 @@ class Function:
         self.exported = False
         self.imported = False
         self.statements = []
-        self.returns_type3 = type3types.none
-        self.returns_str = 'None'
+        self.returns_type3 = type3types.none # FIXME: This could be a placeholder
         self.posonlyargs = []
 
 class StructDefinition:
@@ -319,12 +315,11 @@ class ModuleConstantDef:
     """
     A constant definition within a module
     """
-    __slots__ = ('name', 'lineno', 'type3', 'type_str', 'constant', 'data_block', )
+    __slots__ = ('name', 'lineno', 'type3', 'constant', 'data_block', )
 
     name: str
     lineno: int
     type3: Type3
-    type_str: str
     constant: Constant
     data_block: Optional['ModuleDataBlock']
 
@@ -332,7 +327,6 @@ class ModuleConstantDef:
         self.name = name
         self.lineno = lineno
         self.type3 = type3
-        self.type_str = type3.name
         self.constant = constant
         self.data_block = data_block
 
diff --git a/phasm/parser.py b/phasm/parser.py
index 3cadcdc..3f0afbb 100644
--- a/phasm/parser.py
+++ b/phasm/parser.py
@@ -119,12 +119,9 @@ class OurVisitor:
         _not_implemented(not node.args.posonlyargs, 'FunctionDef.args.posonlyargs')
 
         for arg in node.args.args:
-            if not arg.annotation:
-                _raise_static_error(node, 'Type is required')
-
             function.posonlyargs.append(FunctionParam(
                 arg.arg,
-                self.visit_type(module, arg.annotation),
+                self.visit_type(module, arg.annotation) if arg.annotation else None,
             ))
 
         _not_implemented(not node.args.vararg, 'FunctionDef.args.vararg')
@@ -147,9 +144,11 @@ class OurVisitor:
             else:
                 function.imported = True
 
-        if node.returns:
+        if node.returns is not None: # Note: `-> None` would be a ast.Constant
             function.returns_type3 = self.visit_type(module, node.returns)
-            function.returns_str = function.returns_type3.name
+        else:
+            # Mostly works already, needs to fix Function.returns_type3 and have it updated
+            raise NotImplementedError('Function without an explicit return type')
 
         _not_implemented(not node.type_comment, 'FunctionDef.type_comment')