# must fail: codecs_upper_prefix
# an element beginning WAI is read as classical (codecs::is_wai_element)
diff --git a/wai/wai-rs/src/http_binding/codecs.rs b/wai/wai-rs/src/http_binding/codecs.rs
index 530ae822..cdc19410 100644
--- a/wai/wai-rs/src/http_binding/codecs.rs
+++ b/wai/wai-rs/src/http_binding/codecs.rs
@@ -156,7 +156,7 @@ pub fn parse_element(s: &str) -> Result<Element, CodecsError> {
 /// any ASCII case. Such an element that is not a well-formed `wai1.` or `wai2.` element
 /// is malformed, never classical.
 fn is_wai_element(e: &str) -> bool {
-    e.as_bytes().get(..3).is_some_and(|b| b.eq_ignore_ascii_case(b"wai"))
+    e.as_bytes().get(..3) == Some(&b"wai"[..])
 }
 
 /// Parse a `codecs` value: one entry per `,`-separated element, `None` for a