diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3e5f520..6d8e054 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,6 +21,7 @@ jobs:
       - uses: dtolnay/rust-toolchain@master
         with:
           toolchain: ${{matrix.rust}}
+          components: rust-src
       - run: cargo test --all
         env:
           RUSTFLAGS: ${{matrix.rustflags}}
diff --git a/rust-toolchain.toml b/rust-toolchain.toml
new file mode 100644
index 0000000..20fe888
--- /dev/null
+++ b/rust-toolchain.toml
@@ -0,0 +1,2 @@
+[toolchain]
+components = ["rust-src"]
diff --git a/tests/ui/no-display.stderr b/tests/ui/no-display.stderr
index 8af2452..bd6924b 100644
--- a/tests/ui/no-display.stderr
+++ b/tests/ui/no-display.stderr
@@ -1,12 +1,23 @@
 error[E0599]: the method `as_display` exists for reference `&NoDisplay`, but its trait bounds were not satisfied
- --> $DIR/no-display.rs:7:9
-  |
-4 | struct NoDisplay;
-  | ----------------- doesn't satisfy `NoDisplay: std::fmt::Display`
+   --> $DIR/tests/ui/no-display.rs:7:9
+    |
+4   | struct NoDisplay;
+    | ----------------- doesn't satisfy `NoDisplay: std::fmt::Display`
 ...
-7 | #[error("thread: {thread}")]
-  |         ^^^^^^^^^^^^^^^^^^ method cannot be called on `&NoDisplay` due to unsatisfied trait bounds
-  |
-  = note: the following trait bounds were not satisfied:
-          `NoDisplay: std::fmt::Display`
-          which is required by `&NoDisplay: DisplayAsDisplay`
+7   | #[error("thread: {thread}")]
+    |         ^^^^^^^^^^^^^^^^^^ method cannot be called on `&NoDisplay` due to unsatisfied trait bounds
+    |
+    = note: the following trait bounds were not satisfied:
+            `NoDisplay: std::fmt::Display`
+            which is required by `&NoDisplay: DisplayAsDisplay`
+note: the following trait must be implemented
+   --> $RUST/core/src/fmt/mod.rs
+    |
+    | / pub trait Display {
+    | |     /// Formats the value using the given formatter.
+    | |     ///
+    | |     /// # Examples
+...   |
+    | |     fn fmt(&self, f: &mut Formatter<'_>) -> Result;
+    | | }
+    | |_^
diff --git a/tests/ui/source-enum-not-error.stderr b/tests/ui/source-enum-not-error.stderr
index 2bf7aea..2b5bb17 100644
--- a/tests/ui/source-enum-not-error.stderr
+++ b/tests/ui/source-enum-not-error.stderr
@@ -1,17 +1,28 @@
 error[E0599]: the method `as_dyn_error` exists for reference `&NotError`, but its trait bounds were not satisfied
-  --> $DIR/source-enum-not-error.rs:10:9
-   |
-4  | pub struct NotError;
-   | --------------------
-   | |
-   | doesn't satisfy `NotError: AsDynError`
-   | doesn't satisfy `NotError: std::error::Error`
+   --> $DIR/tests/ui/source-enum-not-error.rs:10:9
+    |
+4   | pub struct NotError;
+    | --------------------
+    | |
+    | doesn't satisfy `NotError: AsDynError`
+    | doesn't satisfy `NotError: std::error::Error`
 ...
-10 |         source: NotError,
-   |         ^^^^^^ method cannot be called on `&NotError` due to unsatisfied trait bounds
-   |
-   = note: the following trait bounds were not satisfied:
-           `NotError: std::error::Error`
-           which is required by `NotError: AsDynError`
-           `&NotError: std::error::Error`
-           which is required by `&NotError: AsDynError`
+10  |         source: NotError,
+    |         ^^^^^^ method cannot be called on `&NotError` due to unsatisfied trait bounds
+    |
+    = note: the following trait bounds were not satisfied:
+            `NotError: std::error::Error`
+            which is required by `NotError: AsDynError`
+            `&NotError: std::error::Error`
+            which is required by `&NotError: AsDynError`
+note: the following trait must be implemented
+   --> $RUST/std/src/error.rs
+    |
+    | / pub trait Error: Debug + Display {
+    | |     /// The lower-level source of this error, if any.
+    | |     ///
+    | |     /// # Examples
+...   |
+    | |     }
+    | | }
+    | |_^
diff --git a/tests/ui/source-struct-not-error.stderr b/tests/ui/source-struct-not-error.stderr
index 7a2c0fe..0325314 100644
--- a/tests/ui/source-struct-not-error.stderr
+++ b/tests/ui/source-struct-not-error.stderr
@@ -1,16 +1,27 @@
 error[E0599]: the method `as_dyn_error` exists for struct `NotError`, but its trait bounds were not satisfied
- --> $DIR/source-struct-not-error.rs:9:5
-  |
-4 | struct NotError;
-  | ----------------
-  | |
-  | method `as_dyn_error` not found for this
-  | doesn't satisfy `NotError: AsDynError`
-  | doesn't satisfy `NotError: std::error::Error`
+   --> $DIR/tests/ui/source-struct-not-error.rs:9:5
+    |
+4   | struct NotError;
+    | ----------------
+    | |
+    | method `as_dyn_error` not found for this
+    | doesn't satisfy `NotError: AsDynError`
+    | doesn't satisfy `NotError: std::error::Error`
 ...
-9 |     source: NotError,
-  |     ^^^^^^ method cannot be called on `NotError` due to unsatisfied trait bounds
-  |
-  = note: the following trait bounds were not satisfied:
-          `NotError: std::error::Error`
-          which is required by `NotError: AsDynError`
+9   |     source: NotError,
+    |     ^^^^^^ method cannot be called on `NotError` due to unsatisfied trait bounds
+    |
+    = note: the following trait bounds were not satisfied:
+            `NotError: std::error::Error`
+            which is required by `NotError: AsDynError`
+note: the following trait must be implemented
+   --> $RUST/std/src/error.rs
+    |
+    | / pub trait Error: Debug + Display {
+    | |     /// The lower-level source of this error, if any.
+    | |     ///
+    | |     /// # Examples
+...   |
+    | |     }
+    | | }
+    | |_^