diff --git a/src/main/scala/scala/xml/PrettyPrinter.scala b/src/main/scala/scala/xml/PrettyPrinter.scala
index 515c9c088..a175f1df2 100755
--- a/src/main/scala/scala/xml/PrettyPrinter.scala
+++ b/src/main/scala/scala/xml/PrettyPrinter.scala
@@ -244,7 +244,7 @@ class PrettyPrinter(width: Int, step: Int) {
    *  @param pscope the namespace to prefix mapping
    *  @return      the formatted string
    */
-  def format(n: Node, pscope: NamespaceBinding = null): String =
+  def format(n: Node, pscope: NamespaceBinding = TopScope): String =
     sbToString(format(n, pscope, _))
 
   /**
diff --git a/src/test/scala/scala/xml/XMLTest.scala b/src/test/scala/scala/xml/XMLTest.scala
index b86f2c9ef..01431baf1 100644
--- a/src/test/scala/scala/xml/XMLTest.scala
+++ b/src/test/scala/scala/xml/XMLTest.scala
@@ -824,4 +824,16 @@ expected closing tag of foo
     }
   }
 
+  @UnitTest
+  def issue28: Unit = {
+    val x = <x:foo xmlns:x="gaga"/>
+    // val ns = new NamespaceBinding("x", "gaga", sc)
+    // val x = Elem("x", "foo", e, ns)
+    val pp = new xml.PrettyPrinter(80, 2)
+    // This assertion passed
+    assertEquals("""<x:foo xmlns:x="gaga"/>""", x.toString)
+    // This was the bug, producing an errant xmlns attribute
+    assertEquals("""<x:foo xmlns:x="gaga"/>""", pp.format(x))
+  }
+
 }