diff --git a/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs b/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs
index 4bf4df226e17..f5bd497135ff 100644
--- a/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs
+++ b/compiler/rustc_mir/src/borrow_check/diagnostics/conflict_errors.rs
@@ -1568,6 +1568,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
                         "borrow occurs due to deref coercion to `{}`",
                         deref_target_ty
                     ));
+                    err.span_note(tcx.def_span(instance.def_id()), "deref defined here");
                 }
             }
         }
diff --git a/src/test/ui/borrowck/issue-81365-1.stderr b/src/test/ui/borrowck/issue-81365-1.stderr
index f680cd629d2f..ef88d7f14a39 100644
--- a/src/test/ui/borrowck/issue-81365-1.stderr
+++ b/src/test/ui/borrowck/issue-81365-1.stderr
@@ -9,6 +9,11 @@ LL |         first;
    |         ----- borrow later used here
    |
    = note: borrow occurs due to deref coercion to `DerefTarget`
+note: deref defined here
+  --> $DIR/issue-81365-1.rs:12:5
+   |
+LL |     type Target = DerefTarget;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/issue-81365-2.stderr b/src/test/ui/borrowck/issue-81365-2.stderr
index 851cc4b1af29..e71edb509649 100644
--- a/src/test/ui/borrowck/issue-81365-2.stderr
+++ b/src/test/ui/borrowck/issue-81365-2.stderr
@@ -9,6 +9,11 @@ LL |         first;
    |         ----- borrow later used here
    |
    = note: borrow occurs due to deref coercion to `DerefTarget`
+note: deref defined here
+  --> $DIR/issue-81365-2.rs:12:5
+   |
+LL |     type Target = DerefTarget;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/issue-81365-3.stderr b/src/test/ui/borrowck/issue-81365-3.stderr
index eedbed3cfe6c..70bb6bb93a94 100644
--- a/src/test/ui/borrowck/issue-81365-3.stderr
+++ b/src/test/ui/borrowck/issue-81365-3.stderr
@@ -9,6 +9,11 @@ LL |         first;
    |         ----- borrow later used here
    |
    = note: borrow occurs due to deref coercion to `Container`
+note: deref defined here
+  --> $DIR/issue-81365-3.rs:23:5
+   |
+LL |     type Target = Container;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/issue-81365-4.stderr b/src/test/ui/borrowck/issue-81365-4.stderr
index 82c9fbbc16f6..e714bb86d1cd 100644
--- a/src/test/ui/borrowck/issue-81365-4.stderr
+++ b/src/test/ui/borrowck/issue-81365-4.stderr
@@ -9,6 +9,11 @@ LL |         first;
    |         ----- borrow later used here
    |
    = note: borrow occurs due to deref coercion to `Container`
+note: deref defined here
+  --> $DIR/issue-81365-4.rs:24:5
+   |
+LL |     type Target = Container;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/issue-81365-5.stderr b/src/test/ui/borrowck/issue-81365-5.stderr
index 8085faf82ed0..7c0e9f43bd0b 100644
--- a/src/test/ui/borrowck/issue-81365-5.stderr
+++ b/src/test/ui/borrowck/issue-81365-5.stderr
@@ -9,6 +9,11 @@ LL |         first;
    |         ----- borrow later used here
    |
    = note: borrow occurs due to deref coercion to `DerefTarget`
+note: deref defined here
+  --> $DIR/issue-81365-5.rs:19:5
+   |
+LL |     type Target = DerefTarget;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/issue-81365-6.stderr b/src/test/ui/borrowck/issue-81365-6.stderr
index d35d12b9a8b5..85ed6acca3d4 100644
--- a/src/test/ui/borrowck/issue-81365-6.stderr
+++ b/src/test/ui/borrowck/issue-81365-6.stderr
@@ -9,6 +9,11 @@ LL |         first;
    |         ----- borrow later used here
    |
    = note: borrow occurs due to deref coercion to `[()]`
+note: deref defined here
+  --> $DIR/issue-81365-6.rs:9:5
+   |
+LL |     type Target = [()];
+   |     ^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/issue-81365-7.stderr b/src/test/ui/borrowck/issue-81365-7.stderr
index 0ee9fb828211..506732ec0c5b 100644
--- a/src/test/ui/borrowck/issue-81365-7.stderr
+++ b/src/test/ui/borrowck/issue-81365-7.stderr
@@ -9,6 +9,11 @@ LL |     first;
    |     ----- borrow later used here
    |
    = note: borrow occurs due to deref coercion to `DerefTarget`
+note: deref defined here
+  --> $DIR/issue-81365-7.rs:12:5
+   |
+LL |     type Target = DerefTarget;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error
 
diff --git a/src/test/ui/borrowck/issue-81365-8.stderr b/src/test/ui/borrowck/issue-81365-8.stderr
index 0656c65c8232..716b6e9b51fd 100644
--- a/src/test/ui/borrowck/issue-81365-8.stderr
+++ b/src/test/ui/borrowck/issue-81365-8.stderr
@@ -9,6 +9,11 @@ LL |         first;
    |         ----- borrow later used here
    |
    = note: borrow occurs due to deref coercion to `DerefTarget`
+note: deref defined here
+  --> $DIR/issue-81365-8.rs:12:5
+   |
+LL |     type Target = DerefTarget;
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: aborting due to previous error