diff --git a/tests/ui/crashes/needless_lifetimes_impl_trait.fixed b/tests/ui/crashes/needless_lifetimes_impl_trait.fixed
index 8bd9eea75bb..837069cae6d 100644
--- a/tests/ui/crashes/needless_lifetimes_impl_trait.fixed
+++ b/tests/ui/crashes/needless_lifetimes_impl_trait.fixed
@@ -9,7 +9,7 @@ struct Baz<'a> {
     bar: &'a Bar,
 }
 
-impl<'a> Foo for Baz<'a> {}
+impl Foo for Baz<'_> {}
 
 impl Bar {
     fn baz(&self) -> impl Foo + '_ {
diff --git a/tests/ui/crashes/needless_lifetimes_impl_trait.stderr b/tests/ui/crashes/needless_lifetimes_impl_trait.stderr
index 3a2d1f4410e..bed6aab25c4 100644
--- a/tests/ui/crashes/needless_lifetimes_impl_trait.stderr
+++ b/tests/ui/crashes/needless_lifetimes_impl_trait.stderr
@@ -1,8 +1,8 @@
 error: the following explicit lifetimes could be elided: 'a
-  --> tests/ui/crashes/needless_lifetimes_impl_trait.rs:15:12
+  --> tests/ui/crashes/needless_lifetimes_impl_trait.rs:12:6
    |
-LL |     fn baz<'a>(&'a self) -> impl Foo + 'a {
-   |            ^^   ^^                     ^^
+LL | impl<'a> Foo for Baz<'a> {}
+   |      ^^              ^^
    |
 note: the lint level is defined here
   --> tests/ui/crashes/needless_lifetimes_impl_trait.rs:1:9
@@ -11,9 +11,21 @@ LL | #![deny(clippy::needless_lifetimes)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^
 help: elide the lifetimes
    |
+LL - impl<'a> Foo for Baz<'a> {}
+LL + impl Foo for Baz<'_> {}
+   |
+
+error: the following explicit lifetimes could be elided: 'a
+  --> tests/ui/crashes/needless_lifetimes_impl_trait.rs:15:12
+   |
+LL |     fn baz<'a>(&'a self) -> impl Foo + 'a {
+   |            ^^   ^^                     ^^
+   |
+help: elide the lifetimes
+   |
 LL -     fn baz<'a>(&'a self) -> impl Foo + 'a {
 LL +     fn baz(&self) -> impl Foo + '_ {
    |
 
-error: aborting due to 1 previous error
+error: aborting due to 2 previous errors
 
diff --git a/tests/ui/extra_unused_lifetimes.rs b/tests/ui/extra_unused_lifetimes.rs
index cdfaf8d3afe..17d2ed9f50c 100644
--- a/tests/ui/extra_unused_lifetimes.rs
+++ b/tests/ui/extra_unused_lifetimes.rs
@@ -114,9 +114,17 @@ pub trait Source {
         fn hey();
     }
 
+    // Should lint. The response to the above comment incorrectly called this a false positive. The
+    // lifetime `'a` can be removed, as demonstrated below.
     impl<'a, T: Source + ?Sized + 'a> Source for Box<T> {
         fn hey() {}
     }
+
+    struct OtherBox<T: ?Sized>(Box<T>);
+
+    impl<T: Source + ?Sized> Source for OtherBox<T> {
+        fn hey() {}
+    }
 }
 
 // Should not lint
diff --git a/tests/ui/extra_unused_lifetimes.stderr b/tests/ui/extra_unused_lifetimes.stderr
index 56292cb5d1a..85fbb7568ff 100644
--- a/tests/ui/extra_unused_lifetimes.stderr
+++ b/tests/ui/extra_unused_lifetimes.stderr
@@ -37,5 +37,11 @@ error: this lifetime isn't used in the function definition
 LL |         pub fn something<'c>() -> Self {
    |                          ^^
 
-error: aborting due to 6 previous errors
+error: this lifetime isn't used in the impl
+  --> tests/ui/extra_unused_lifetimes.rs:119:10
+   |
+LL |     impl<'a, T: Source + ?Sized + 'a> Source for Box<T> {
+   |          ^^
+
+error: aborting due to 7 previous errors
 
diff --git a/tests/ui/needless_lifetimes.fixed b/tests/ui/needless_lifetimes.fixed
index d1787b35abd..e4bb7f86d12 100644
--- a/tests/ui/needless_lifetimes.fixed
+++ b/tests/ui/needless_lifetimes.fixed
@@ -329,7 +329,7 @@ mod issue2944 {
         bar: &'a Bar,
     }
 
-    impl<'a> Foo for Baz<'a> {}
+    impl Foo for Baz<'_> {}
     impl Bar {
         fn baz(&self) -> impl Foo + '_ {
             Baz { bar: self }
diff --git a/tests/ui/needless_lifetimes.stderr b/tests/ui/needless_lifetimes.stderr
index 50f845e2d92..166e6d0eabf 100644
--- a/tests/ui/needless_lifetimes.stderr
+++ b/tests/ui/needless_lifetimes.stderr
@@ -335,6 +335,18 @@ LL -         fn needless_lt<'a>(_x: &'a u8) {}
 LL +         fn needless_lt(_x: &u8) {}
    |
 
+error: the following explicit lifetimes could be elided: 'a
+  --> tests/ui/needless_lifetimes.rs:332:10
+   |
+LL |     impl<'a> Foo for Baz<'a> {}
+   |          ^^              ^^
+   |
+help: elide the lifetimes
+   |
+LL -     impl<'a> Foo for Baz<'a> {}
+LL +     impl Foo for Baz<'_> {}
+   |
+
 error: the following explicit lifetimes could be elided: 'a
   --> tests/ui/needless_lifetimes.rs:334:16
    |
@@ -564,5 +576,5 @@ LL -         fn one_input<'a>(x: &'a u8) -> &'a u8 {
 LL +         fn one_input(x: &u8) -> &u8 {
    |
 
-error: aborting due to 47 previous errors
+error: aborting due to 48 previous errors