diff --git a/library/core/src/str/mod.rs b/library/core/src/str/mod.rs
index c4f2e283eb3bc..ee66895a7ed2a 100644
--- a/library/core/src/str/mod.rs
+++ b/library/core/src/str/mod.rs
@@ -2353,7 +2353,7 @@ impl str {
     #[inline]
     pub fn is_ascii(&self) -> bool {
         // We can treat each byte as character here: all multibyte characters
-        // start with a byte that is not in the ascii range, so we will stop
+        // start with a byte that is not in the ASCII range, so we will stop
         // there already.
         self.as_bytes().is_ascii()
     }