diff --git a/src/libstd/ascii.rs b/src/libstd/ascii.rs
index a8a3353da4c0..3ae3cf8504ea 100644
--- a/src/libstd/ascii.rs
+++ b/src/libstd/ascii.rs
@@ -567,4 +567,10 @@ mod tests {
                     &from_u32(lower).unwrap().to_string()));
         }
     }
+
+    #[test]
+    fn inference_works() {
+        let x = "a".to_string();
+        x.eq_ignore_ascii_case("A");
+    }
 }