diff --git a/hm-inference/ast_visitor.py b/hm-inference/ast_visitor.py
index b1b6cad..bd453b1 100644
--- a/hm-inference/ast_visitor.py
+++ b/hm-inference/ast_visitor.py
@@ -57,7 +57,7 @@ class Visitor(ast.NodeVisitor):
                      {keyword.arg: keyword.value.type for keyword
                       in node.keywords}, node.type)
         node.func.type.unify(call)
-        self.calls.append(node.func.type)
+        self.calls.append(call)
 
     def visit_Attribute(self, node):
         self.visit(node.value)
@@ -158,3 +158,4 @@ class Visitor(ast.NodeVisitor):
         node.test.type.unify(TBool)
         for stmt in chain(node.body, node.orelse):
             self.visit(stmt)
+
diff --git a/hm-inference/nac3_types.py b/hm-inference/nac3_types.py
index b176b78..8bd96bf 100644
--- a/hm-inference/nac3_types.py
+++ b/hm-inference/nac3_types.py
@@ -63,7 +63,7 @@ class TVar(Type):
         if self.range is not None:
             ty = self.find()
             # maybe we should replace this with explicit eq
-            if ty not in self.range:
+            if ty is not self and ty not in self.range:
                 raise UnificationError(
                     f'{self.id} cannot be substituted by {ty}')
 
@@ -125,10 +125,10 @@ class TVar(Type):
                     if k not in x.fields:
                         raise UnificationError(
                             f'Cannot unify {y} with {x}')
-                    if isinstance(v, TFunc):
+                    if isinstance(v, TFunc) and not v.instantiated:
                         v = v.instantiate()
                     u = x.fields[k]
-                    if isinstance(u, TFunc):
+                    if isinstance(u, TFunc) and not u.instantiated:
                         u = u.instantiate()
                     v.unify(u)
             if isinstance(x, TList):
@@ -168,8 +168,7 @@ class TCall(Type):
         self.fun = TVar()
 
     def check(self):
-        for arg in chain(self.posargs, self.kwargs.values()):
-            arg.check()
+        self.fun.find().check()
 
     def find(self):
         if isinstance(self.fun.find(), TVar):
@@ -327,6 +326,9 @@ class TList(Type):
     def __init__(self, param: Type):
         self.param = param
 
+    def check(self):
+        self.param.check()
+
     def unify(self, other):
         other = other.find()
         if isinstance(other, TVar):
@@ -344,6 +346,10 @@ class TTuple(Type):
     def __init__(self, params: List[Type]):
         self.params = params
 
+    def check(self):
+        for p in self.params:
+            p.check()
+
     def unify(self, other):
         other = other.find()
         if isinstance(other, TVar):
diff --git a/hm-inference/test.py b/hm-inference/test.py
index 0e6a75b..9763537 100644
--- a/hm-inference/test.py
+++ b/hm-inference/test.py
@@ -1,11 +1,11 @@
-# from __future__ import annotations
+from __future__ import annotations
 import ast
 from ast_visitor import Visitor
 from nac3_types import *
 
 
 var = TVar([TInt, TBool])
-var2 = TVar()
+var2 = TVar([TInt])
 
 foo = TObj('Foo', {
     'foo': TFunc([
@@ -26,10 +26,14 @@ for key, value in v.assignments.items():
 print('-----------')
 
 src = """
+# a = Foo(1).foo(1, 2)
+# b = Foo(1).foo(1, True)
+# c = Foo(True).foo(True, 1)
+# d = Foo(True).foo(True, True)
+
 a = Foo(1).foo(1, 2)
-b = Foo(1).foo(1, True)
-c = Foo(True).foo(True, 1)
-d = Foo(True).foo(True, True)
+c = y.foo(True, 1)
+y = Foo(True)
 """
 
 print(src)