diff --git a/DOMTEST b/DOMTEST
index 75bd0ba..f6b14b1 100644
--- a/DOMTEST
+++ b/DOMTEST
@@ -1151,15 +1151,12 @@ TEST FAILED: There is no applicable method for the generic function
              when called with arguments
                (#(116 101 115 116) NIL).
 760/808 nodesetprefix05.xml
-TEST FAILED: expected exception NAMESPACE_ERR
+TEST FAILED: The variable CXML::*CTX* is unbound.
 761/808 nodesetprefix06.xml
-TEST FAILED: expected exception NAMESPACE_ERR
 762/808 nodesetprefix07.xml
-TEST FAILED: expected exception NAMESPACE_ERR
 763/808 nodesetprefix08.xml
-TEST FAILED: expected exception NAMESPACE_ERR
 764/808 nodesetprefix09.xml
-TEST FAILED: expected exception INVALID_CHARACTER_ERR
+TEST FAILED: The variable CXML::*CTX* is unbound.
 765/808 normalize01.xml
 766/808 ownerDocument01.xml
 767/808 ownerElement01.xml
@@ -1169,17 +1166,13 @@ TEST FAILED: expected exception INVALID_CHARACTER_ERR
 771/808 prefix03.xml
 772/808 prefix04.xml
 773/808 prefix05.xml
-TEST FAILED: expected exception NAMESPACE_ERR
 774/808 prefix06.xml
-TEST FAILED: expected exception INVALID_CHARACTER_ERR
 775/808 prefix07.xml
-TEST FAILED: expected exception NAMESPACE_ERR
+TEST FAILED: The variable CXML::*CTX* is unbound.
 776/808 prefix08.xml
-TEST FAILED: expected exception NO_MODIFICATION_ALLOWED_ERR
 777/808 prefix09.xml
 TEST FAILED: expected exception NAMESPACE_ERR
 778/808 prefix10.xml
-TEST FAILED: expected exception NAMESPACE_ERR
 779/808 prefix11.xml
 TEST FAILED: expected exception NAMESPACE_ERR
 780/808 publicId01.xml
@@ -1245,4 +1238,4 @@ TEST FAILED: There is no applicable method for the generic function
              when called with arguments
                (NIL).
 805/808 systemId01.xml
-143/763 tests failed; 45 tests were skipped
\ No newline at end of file
+136/763 tests failed; 45 tests were skipped
\ No newline at end of file
diff --git a/dom/dom-impl.lisp b/dom/dom-impl.lisp
index 915caaf..191f4c8 100644
--- a/dom/dom-impl.lisp
+++ b/dom/dom-impl.lisp
@@ -39,10 +39,15 @@
 (defmethod dom:namespace-uri ((node node)) nil)
 
 (defclass namespace-mixin ()
-  ((prefix        :initarg :prefix        :accessor dom:prefix)
+  ((prefix        :initarg :prefix        :reader dom:prefix)
    (local-name    :initarg :local-name    :reader dom:local-name)
    (namespace-uri :initarg :namespace-uri :reader dom:namespace-uri)))
 
+(defmethod (setf dom:prefix) (newval (node namespace-mixin))
+  (assert-writeable node)
+  (safe-split-qname (concatenate 'rod newval #":foo") (dom:namespace-uri node))
+  (setf (slot-value node 'prefix) newval))
+
 (defclass document (node)
   ((doc-type    :initarg :doc-type     :reader dom:doctype)
    (dtd         :initform nil          :reader dtd)