diff --git a/src/test/ui/invalid/invalid-variadic-function.stderr b/src/test/ui/invalid/invalid-variadic-function.stderr
index b2dbf8b91908..fd20bd84edc4 100644
--- a/src/test/ui/invalid/invalid-variadic-function.stderr
+++ b/src/test/ui/invalid/invalid-variadic-function.stderr
@@ -1,4 +1,4 @@
-error: only foreign functions are allowed to be C-variadic
+error[E0743]: only foreign functions are allowed to be C-variadic
   --> $DIR/invalid-variadic-function.rs:1:26
    |
 LL | extern "C" fn foo(x: u8, ...);
@@ -12,3 +12,4 @@ LL | extern "C" fn foo(x: u8, ...);
 
 error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0743`.
diff --git a/src/test/ui/parser/variadic-ffi-3.stderr b/src/test/ui/parser/variadic-ffi-3.stderr
index 8ea4d194396f..aeeebdb99148 100644
--- a/src/test/ui/parser/variadic-ffi-3.stderr
+++ b/src/test/ui/parser/variadic-ffi-3.stderr
@@ -1,4 +1,4 @@
-error: only foreign functions are allowed to be C-variadic
+error[E0743]: only foreign functions are allowed to be C-variadic
   --> $DIR/variadic-ffi-3.rs:1:18
    |
 LL | fn foo(x: isize, ...) {
@@ -6,3 +6,4 @@ LL | fn foo(x: isize, ...) {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0743`.
diff --git a/src/test/ui/parser/variadic-ffi-4.stderr b/src/test/ui/parser/variadic-ffi-4.stderr
index 69fbf84869c1..da83276c72dd 100644
--- a/src/test/ui/parser/variadic-ffi-4.stderr
+++ b/src/test/ui/parser/variadic-ffi-4.stderr
@@ -1,4 +1,4 @@
-error: only foreign functions are allowed to be C-variadic
+error[E0743]: only foreign functions are allowed to be C-variadic
   --> $DIR/variadic-ffi-4.rs:1:29
    |
 LL | extern "C" fn foo(x: isize, ...) {
@@ -6,3 +6,4 @@ LL | extern "C" fn foo(x: isize, ...) {
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0743`.