diff --git a/schala-lang/language/src/typechecking.rs b/schala-lang/language/src/typechecking.rs
index 4abbc00..635362d 100644
--- a/schala-lang/language/src/typechecking.rs
+++ b/schala-lang/language/src/typechecking.rs
@@ -6,7 +6,9 @@ use util::ScopeStack;
 pub type TypeName = Rc<String>;
 
 pub struct TypeContext<'a> {
-  variable_map: ScopeStack<'a, Rc<String>, Type<()>>
+  variable_map: ScopeStack<'a, Rc<String>, Type<()>>,
+  evar_count: u32
+
 }
 
 type InferResult<T> = Result<T, TypeError>;
@@ -21,13 +23,20 @@ impl TypeError {
 }
 
 #[derive(Debug, Clone)]
-enum Type<a> {
-  Var(a),
+enum Type<A> {
+  Var(A),
   Const(TConst),
-  Arrow(Box<Type<a>>, Box<Type<a>>),
-  ExistentialVar(u32)
+  Arrow(Box<Type<A>>, Box<Type<A>>),
 }
 
+enum TVar {
+  Universal(UniversalVar),
+  Existential(ExistentialVar)
+}
+
+struct UniversalVar(Rc<String>);
+struct ExistentialVar(u32);
+
 impl TypeIdentifier {
   fn to_monotype(&self) -> Type<()> {
     match self {
@@ -73,6 +82,7 @@ impl<'a> TypeContext<'a> {
   pub fn new() -> TypeContext<'a> {
     TypeContext { 
       variable_map: ScopeStack::new(None),
+      evar_count: 0
     }
   }
 
@@ -180,8 +190,10 @@ impl<'a> TypeContext<'a> {
     unimplemented!()
   }
 
-  fn allocate_existential(&mut self) -> Type<()> {
-    Type::ExistentialVar(0)
+  fn allocate_existential(&mut self) -> Type<TVar> {
+    let n = self.evar_count;
+    self.evar_count += 1;
+    Type::Var(TVar::Existential(ExistentialVar(n)))
   }
 }