diff --git a/src/indices.lisp b/src/indices.lisp
index a2d4030..66741d2 100644
--- a/src/indices.lisp
+++ b/src/indices.lisp
@@ -21,9 +21,8 @@
 
 (defun all-tags ()
   "Retrieve a list of all tags used in posts."
-  (sort (reduce (lambda (x y) (union x y :test #'string=))
-                (mapcar #'post-tags (hash-table-values *posts*)))
-        #'string<))
+  (sort (remove-duplicates (mappend 'post-tags (hash-table-values *posts*))
+                           :test #'string=) #'string<))
 
 (defun get-month (timestamp)
   "Extract the YYYY-MM portion of TIMESTAMP."
diff --git a/src/packages.lisp b/src/packages.lisp
index 2652d73..ffc91d8 100644
--- a/src/packages.lisp
+++ b/src/packages.lisp
@@ -2,7 +2,8 @@
   (:documentation "Homepage: <a href=\"http://github.com/redline6561/coleslaw\">Github</a>")
   (:use :cl)
   (:import-from :alexandria #:hash-table-values
-                            #:make-keyword)
+                            #:make-keyword
+                            #:mappend)
   (:import-from :closure-template #:compile-template)
   (:export #:main
            #:add-injection