diff --git a/types_.py b/types_.py
index bf62656..643d758 100644
--- a/types_.py
+++ b/types_.py
@@ -65,7 +65,11 @@ class FunctionTy:
 		return self.arg_type.free_vars() | self.ret_type.free_vars()
 
 	def __repr__(self) -> str:
-		return f'({self.arg_type}) -> {self.ret_type}'
+		arg = repr(self.arg_type)
+		if ' ' in arg:
+			return f'({arg}) -> {self.ret_type}'
+		else:
+			return f'{arg} -> {self.ret_type}'
 
 @dataclass(frozen=True)
 class HoleTy: