diff --git a/src/macaw/core.clj b/src/macaw/core.clj
index 2eb00d5..962c5d3 100644
--- a/src/macaw/core.clj
+++ b/src/macaw/core.clj
@@ -17,8 +17,8 @@
 
   (Specifically, it returns their fully-qualified names as strings, where 'fully-qualified' means 'as found in the query'.)"
   [^Statement parsed-query]
-  (let [column-names (atom #{})
-        table-names  (atom #{})
+  (let [column-names (transient #{})
+        table-names  (transient #{})
         ast-walker (ASTWalker. {:column (fn [^Column column]
                                           (swap! column-names conj (.getColumnName column)))
                                 :table  (fn [^Table table]