diff --git a/src/fn/closures.md b/src/fn/closures.md
index a0a33efba1..0c1b999efd 100644
--- a/src/fn/closures.md
+++ b/src/fn/closures.md
@@ -34,6 +34,9 @@ fn main() {
     println!("function: {}", function(i));
     println!("closure_annotated: {}", closure_annotated(i));
     println!("closure_inferred: {}", closure_inferred(i));
+    // Once closure's type has been inferred, it cannot be inferred again with another type.
+    //println!("cannot reuse closure_inferred with another type: {}", closure_inferred(42i64));
+    // TODO: uncomment the line above and see the compiler error.
 
     // A closure taking no arguments which returns an `i32`.
     // The return type is inferred.