diff --git a/src/babashka/impl/classes.clj b/src/babashka/impl/classes.clj
index e89a981a..daa43be7 100644
--- a/src/babashka/impl/classes.clj
+++ b/src/babashka/impl/classes.clj
@@ -249,6 +249,7 @@
     :instance-checks [clojure.lang.Cons
                       clojure.lang.Cycle
                       clojure.lang.IObj
+                      clojure.lang.Fn ;; to distinguish fns from maps, etc.
                       clojure.lang.IFn
                       clojure.lang.IPending
                       ;; clojure.lang.IDeref