diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 4d000691b8b5f..3b434bdfe2c61 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -1611,7 +1611,7 @@ pub trait UpperExp: PointeeSized {
 ///
 /// let mut output = String::new();
 /// fmt::write(&mut output, format_args!("Hello {}!", "world"))
-///     .expect("Error occurred while trying to write in String");
+///     .expect("writing to a String should never fail");
 /// assert_eq!(output, "Hello world!");
 /// ```
 ///
@@ -1622,7 +1622,7 @@ pub trait UpperExp: PointeeSized {
 ///
 /// let mut output = String::new();
 /// write!(&mut output, "Hello {}!", "world")
-///     .expect("Error occurred while trying to write in String");
+///     .expect("writing to a String should never fail");
 /// assert_eq!(output, "Hello world!");
 /// ```
 ///