diff --git a/cache.lisp b/cache.lisp
index e8d5658..42323ea 100644
--- a/cache.lisp
+++ b/cache.lisp
@@ -2,6 +2,9 @@
 
 (defvar *parser-cache* (make-hash-table))
 
+(defun drop-parser-cache ()
+  (clrhash *parser-cache*))
+
 ;; parser caching
 
 (defmacro cached? (parser label)
diff --git a/package.lisp b/package.lisp
index 15028d2..d6fc0e2 100644
--- a/package.lisp
+++ b/package.lisp
@@ -1,6 +1,7 @@
 (defpackage :parser-combinators
     (:use :cl :iterate :alexandria)
-  (:export #:result
+  (:export #:drop-parser-cache
+           #:result
            #:zero
            #:item
            #:sat