diff --git a/bindgen/codegen/mod.rs b/bindgen/codegen/mod.rs
index f5518e432d..ddd40d972e 100644
--- a/bindgen/codegen/mod.rs
+++ b/bindgen/codegen/mod.rs
@@ -5906,7 +5906,8 @@ pub(crate) mod utils {
 
             // Check that the suffix starts with '@' and is all ASCII decimals
             // after that.
-            if suffix[0] != b'@' || !suffix[1..].iter().all(u8::is_ascii_digit)
+            if suffix[0] != b'@' ||
+                suffix[1..].iter().any(|&c| !c.is_ascii_digit())
             {
                 return false;
             }