diff --git a/src/libstd/ascii.rs b/src/libstd/ascii.rs
index 031a9b8bec2..f0fd30a3899 100644
--- a/src/libstd/ascii.rs
+++ b/src/libstd/ascii.rs
@@ -669,4 +669,10 @@ mod tests {
                     &from_u32(lower).unwrap().to_string()));
         }
     }
+
+    #[test]
+    fn inference_works() {
+        let x = "a".to_string();
+        x.eq_ignore_ascii_case("A");
+    }
 }