diff --git a/src/test/ui/nll/issue-51191.rs b/src/test/ui/nll/issue-51191.rs
index 638b9b0b63a..836587d93b8 100644
--- a/src/test/ui/nll/issue-51191.rs
+++ b/src/test/ui/nll/issue-51191.rs
@@ -1,9 +1,9 @@
-#![allow(unconditional_recursion)]
-
 struct Struct;
 
 impl Struct {
     fn bar(self: &mut Self) {
+        //~^ WARN function cannot return without recursing
+        //~^^ HELP a `loop` may express intention better if this is on purpose
         (&mut self).bar();
         //~^ ERROR cannot borrow `self` as mutable, as it is not declared as mutable [E0596]
         //~^^ HELP try removing `&mut` here
diff --git a/src/test/ui/nll/issue-51191.stderr b/src/test/ui/nll/issue-51191.stderr
index f2cc78f4b9e..450993425e2 100644
--- a/src/test/ui/nll/issue-51191.stderr
+++ b/src/test/ui/nll/issue-51191.stderr
@@ -1,3 +1,15 @@
+warning: function cannot return without recursing
+  --> $DIR/issue-51191.rs:4:5
+   |
+LL |     fn bar(self: &mut Self) {
+   |     ^^^^^^^^^^^^^^^^^^^^^^^ cannot return without recursing
+...
+LL |         (&mut self).bar();
+   |         ----------------- recursive call site
+   |
+   = note: `#[warn(unconditional_recursion)]` on by default
+   = help: a `loop` may express intention better if this is on purpose
+
 error[E0596]: cannot borrow `self` as mutable, as it is not declared as mutable
   --> $DIR/issue-51191.rs:7:9
    |
@@ -36,6 +48,6 @@ LL |         (&mut self).bar();
    |         cannot borrow as mutable
    |         help: try removing `&mut` here
 
-error: aborting due to 5 previous errors
+error: aborting due to 5 previous errors; 1 warning emitted
 
 For more information about this error, try `rustc --explain E0596`.