diff --git a/src/Core/Syntax.hs b/src/Core/Syntax.hs
index 841cdee..714aa4d 100644
--- a/src/Core/Syntax.hs
+++ b/src/Core/Syntax.hs
@@ -88,6 +88,9 @@ type Expr b = Fix (ExprF b)
 instance IsString (ExprF b a) where
     fromString = VarF . fromString
 
+instance (IsString (f (Fix f))) => IsString (Fix f) where
+    fromString = Fix . fromString
+
 data Type = TyFun
           | TyVar Name
           | TyApp Type Type