diff --git a/serde_derive_internals/src/case.rs b/serde_derive_internals/src/case.rs
index 658a8664..1bdc8238 100644
--- a/serde_derive_internals/src/case.rs
+++ b/serde_derive_internals/src/case.rs
@@ -7,7 +7,7 @@
 // except according to those terms.
 
 // See https://users.rust-lang.org/t/psa-dealing-with-warning-unused-import-std-ascii-asciiext-in-today-s-nightly/13726
-#[allow(unused_imports)]
+#[allow(deprecated, unused_imports)]
 use std::ascii::AsciiExt;
 
 use std::str::FromStr;