diff --git a/src/local-time.lisp b/src/local-time.lisp
index c159cf1b..6da7ff8f 100644
--- a/src/local-time.lisp
+++ b/src/local-time.lisp
@@ -736,10 +736,12 @@ In other words:
                 (push `(%set-timestamp-part ,part ,value) functions))
                ((string= operation :offset)
                 (push `(%offset-timestamp-part ,part ,value) functions))
-               ((or (string= operation :utc-offset)
-                    (string= operation :timezone))
-                (push (second change) params)
-                (push operation params))
+               ((string= operation :utc-offset)
+                (push part params)
+                (push :utc-offset params))
+               ((string= operation :timezone)
+                (push part params)
+                (push :timezone params))
                (t (error "Unexpected operation ~S" operation)))))
       :finally
          (loop
diff --git a/test/simple.lisp b/test/simple.lisp
index 7236e510..5dafdddf 100644
--- a/test/simple.lisp
+++ b/test/simple.lisp
@@ -98,20 +98,20 @@
 
 (deftest test/adjust-timestamp/bug1 ()
   (let* ((timestamp (parse-timestring "2006-01-01T00:00:00Z"))
-         (modified-timestamp (adjust-timestamp timestamp (offset :year 1))))
+         (modified-timestamp (adjust-timestamp timestamp (timezone +utc-zone+) (offset :year 1))))
     (is (timestamp= (parse-timestring "2007-01-01T00:00:00Z") modified-timestamp))))
 
 (deftest test/adjust-timestamp/bug2 ()
   (let* ((timestamp (parse-timestring "2009-03-01T01:00:00.000000+00:00"))
-         (modified-timestamp (adjust-timestamp timestamp (offset :month 1))))
+         (modified-timestamp (adjust-timestamp timestamp (timezone +utc-zone+) (offset :month 1))))
     (is (timestamp= (parse-timestring "2009-04-01T01:00:00.000000+00:00") modified-timestamp))))
 
 (deftest test/adjust-timestamp/bug3 ()
   (let* ((timestamp (parse-timestring "2009-03-01T01:00:00.000000+00:00"))
-         (modified-timestamp (adjust-timestamp timestamp (offset :day-of-week :monday))))
+         (modified-timestamp (adjust-timestamp timestamp (timezone +utc-zone+) (offset :day-of-week :monday))))
     (is (timestamp= (parse-timestring "2009-02-23T01:00:00.000000+00:00") modified-timestamp)))
   (let* ((timestamp (parse-timestring "2009-03-04T01:00:00.000000+00:00"))
-         (modified-timestamp (adjust-timestamp timestamp (offset :day-of-week :monday))))
+         (modified-timestamp (adjust-timestamp timestamp (timezone +utc-zone+) (offset :day-of-week :monday))))
     (is (timestamp= (parse-timestring "2009-03-02T01:00:00.000000+00:00") modified-timestamp))))
 
 #+nil