diff --git a/src/librustc_error_codes/error_codes/E0124.md b/src/librustc_error_codes/error_codes/E0124.md
index a7836526a7dd4..8af7cb819cfaf 100644
--- a/src/librustc_error_codes/error_codes/E0124.md
+++ b/src/librustc_error_codes/error_codes/E0124.md
@@ -1,5 +1,6 @@
-You declared two fields of a struct with the same name. Erroneous code
-example:
+A struct was declared with two fields having the same name.
+
+Erroneous code example:
 
 ```compile_fail,E0124
 struct Foo {
diff --git a/src/librustc_error_codes/error_codes/E0128.md b/src/librustc_error_codes/error_codes/E0128.md
index d0a4b32f9688e..6f8dfe3a73b9e 100644
--- a/src/librustc_error_codes/error_codes/E0128.md
+++ b/src/librustc_error_codes/error_codes/E0128.md
@@ -1,4 +1,5 @@
-Type parameter defaults can only use parameters that occur before them.
+A type parameter with default value is using forward declared identifier.
+
 Erroneous code example:
 
 ```compile_fail,E0128
@@ -7,11 +8,11 @@ struct Foo<T = U, U = ()> {
     field2: U,
 }
 // error: type parameters with a default cannot use forward declared
-// identifiers
+//        identifiers
 ```
 
-Since type parameters are evaluated in-order, you may be able to fix this issue
-by doing:
+Type parameter defaults can only use parameters that occur before them. Since
+type parameters are evaluated in-order, this issue could be fixed by doing:
 
 ```
 struct Foo<U = (), T = U> {