diff --git a/hm-inference/nac3_types.py b/hm-inference/nac3_types.py
index 8bd96bf..9ef519f 100644
--- a/hm-inference/nac3_types.py
+++ b/hm-inference/nac3_types.py
@@ -125,11 +125,7 @@ class TVar(Type):
                     if k not in x.fields:
                         raise UnificationError(
                             f'Cannot unify {y} with {x}')
-                    if isinstance(v, TFunc) and not v.instantiated:
-                        v = v.instantiate()
                     u = x.fields[k]
-                    if isinstance(u, TFunc) and not u.instantiated:
-                        u = u.instantiate()
                     v.unify(u)
             if isinstance(x, TList):
                 if y.type not in [TVarType.UNDETERMINED, TVarType.SEQUENCE, TVarType.LIST]:
@@ -162,63 +158,69 @@ class FuncArg:
 
 class TCall(Type):
     def __init__(self, posargs: List[Type], kwargs: Dict[str, Type], ret: Type):
-        self.posargs = posargs
-        self.kwargs = kwargs
-        self.ret = ret
-        self.fun = TVar()
+        self.calls = [[posargs, kwargs, ret, None]]
+        self.parent = self
+        self.rank = 0
 
     def check(self):
-        self.fun.find().check()
+        self.calls[0][3].check()
 
     def find(self):
-        if isinstance(self.fun.find(), TVar):
-            return self
-        return self.fun.find()
+        root = self
+        parent = self.parent
+        while root is not parent and isinstance(parent, TCall):
+            _, parent = root, root.parent = parent, parent.parent
+        if parent.calls[0][3] is None:
+            return parent
+        return parent.calls[0][3]
 
     def unify(self, other):
-        if not isinstance(self.fun.find(), TVar):
-            self.fun.unify(other)
+        y = self.find()
+        if y is not self:
+            y.unify(other)
             return
 
-        other = other.find()
-        if other is self:
+        x = other.find()
+        if x is y:
             return
 
-        if isinstance(other, TCall):
-            for a, b in zip(self.posargs, other.posargs):
-                a.unify(b)
-            for k, v in self.kwargs.items():
-                if k in other.kwargs:
-                    other.kwargs[k].unify(v)
-                else:
-                    other.kwargs[k] = v
-            for k, v in other.kwargs.items():
-                if k not in self.kwargs:
-                    self.kwargs[k] = v
-            self.fun.unify(other.fun)
-        elif isinstance(other, TFunc):
-            all_args = set(arg.name for arg in other.args)
-            required = set(arg.name for arg in other.args if not
-                           arg.is_optional)
-            other.ret.unify(self.ret)
-            for i, v in enumerate(self.posargs):
-                arg = other.args[i]
-                arg.typ.unify(v)
-                if arg.name in required:
-                    required.remove(arg.name)
-            for k, v in self.kwargs.items():
-                arg = next((arg for arg in other.args if arg.name == k), None)
-                if arg is None:
-                    raise UnificationError(f'Unknown kwarg {k}')
-                if k not in all_args:
-                    raise UnificationError(f'Duplicated kwarg {k}')
-                arg.typ.unify(v)
-                if k in required:
-                    required.remove(k)
-                all_args.remove(k)
-            if len(required) > 0:
-                raise UnificationError(f'Missing arguments')
-            self.fun.unify(other)
+        if isinstance(x, TCall):
+            # standard union find
+            if x.rank < y.rank:
+                x, y = y, x
+            y.parent = x
+            if x.rank == y.rank:
+                x.rank += 1
+            x.calls += y.calls
+        elif isinstance(x, TFunc):
+            fn = x
+            for i in range(len(y.calls)):
+                posargs, kwargs, ret, _ = y.calls[i]
+                c = y.calls[i]
+                c[3] = fn
+                if not x.instantiated:
+                    fn = x.instantiate()
+                all_args = set(arg.name for arg in fn.args)
+                required = set(arg.name for arg in fn.args if not
+                               arg.is_optional)
+                fn.ret.unify(ret)
+                for i, v in enumerate(posargs):
+                    arg = fn.args[i]
+                    arg.typ.unify(v)
+                    if arg.name in required:
+                        required.remove(arg.name)
+                for k, v in kwargs.items():
+                    arg = next((arg for arg in fn.args if arg.name == k), None)
+                    if arg is None:
+                        raise UnificationError(f'Unknown kwarg {k}')
+                    if k not in all_args:
+                        raise UnificationError(f'Duplicated kwarg {k}')
+                    arg.typ.unify(v)
+                    if k in required:
+                        required.remove(k)
+                    all_args.remove(k)
+                if len(required) > 0:
+                    raise UnificationError(f'Missing arguments')
         elif isinstance(other, TVar):
             other.unify(self)
         else:
diff --git a/hm-inference/test.py b/hm-inference/test.py
index 9763537..b8d49a9 100644
--- a/hm-inference/test.py
+++ b/hm-inference/test.py
@@ -5,7 +5,7 @@ from nac3_types import *
 
 
 var = TVar([TInt, TBool])
-var2 = TVar([TInt])
+var2 = TVar([TInt, TBool])
 
 foo = TObj('Foo', {
     'foo': TFunc([
@@ -26,14 +26,13 @@ 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 = f.foo(1, 2)
+b = f.foo(1, True)
+c = g.foo(True, 1)
+d = g.foo(True, True)
 
-a = Foo(1).foo(1, 2)
-c = y.foo(True, 1)
-y = Foo(True)
+f = Foo(1)
+g = Foo(1)
 """
 
 print(src)