diff --git a/ext/java/nokogiri/XmlXpathContext.java b/ext/java/nokogiri/XmlXpathContext.java
index 40599232e42..5996956f68f 100644
--- a/ext/java/nokogiri/XmlXpathContext.java
+++ b/ext/java/nokogiri/XmlXpathContext.java
@@ -154,7 +154,11 @@ public class XmlXpathContext extends RubyObject
   public IRubyObject
   register_ns(IRubyObject prefix, IRubyObject uri)
   {
-    nsContext.registerNamespace(prefix.asJavaString(), uri.asJavaString());
+    if (uri.isNil()) {
+      nsContext.deregisterNamespace(prefix.asJavaString());
+    } else {
+      nsContext.registerNamespace(prefix.asJavaString(), uri.asJavaString());
+    }
     return this;
   }
 
@@ -169,10 +173,23 @@ public class XmlXpathContext extends RubyObject
       variableResolver = NokogiriXPathVariableResolver.create();
       this.variableResolver = variableResolver;
     }
-    variableResolver.registerVariable(name.asJavaString(), value.asJavaString());
+    if (value.isNil()) {
+      variableResolver.deregisterVariable(name.asJavaString());
+    } else {
+      variableResolver.registerVariable(name.asJavaString(), value.asJavaString());
+    }
     return this;
   }
 
+  @JRubyMethod(name = "node=")
+  public IRubyObject
+  set_node(ThreadContext context, IRubyObject rb_node)
+  {
+    this.context = (XmlNode) rb_node;
+    return rb_node;
+  }
+
+
   private IRubyObject
   node_set(ThreadContext context, String expr, IRubyObject handler)
   {
diff --git a/ext/java/nokogiri/internals/NokogiriNamespaceContext.java b/ext/java/nokogiri/internals/NokogiriNamespaceContext.java
index 24381a4c8d0..0ff2920ef40 100644
--- a/ext/java/nokogiri/internals/NokogiriNamespaceContext.java
+++ b/ext/java/nokogiri/internals/NokogiriNamespaceContext.java
@@ -107,4 +107,10 @@ public final class NokogiriNamespaceContext implements NamespaceContext
     register.put(prefix, uri);
   }
 
+  public void
+  deregisterNamespace(String prefix)
+  {
+    if ("xmlns".equals(prefix)) { prefix = ""; }
+    register.remove(prefix);
+  }
 }
diff --git a/ext/java/nokogiri/internals/NokogiriXPathVariableResolver.java b/ext/java/nokogiri/internals/NokogiriXPathVariableResolver.java
index 0c8ca6d29b1..e830f4c6c94 100644
--- a/ext/java/nokogiri/internals/NokogiriXPathVariableResolver.java
+++ b/ext/java/nokogiri/internals/NokogiriXPathVariableResolver.java
@@ -34,4 +34,10 @@ public class NokogiriXPathVariableResolver implements XPathVariableResolver
   {
     variables.put(new QName(name), value);
   }
+  public void
+  deregisterVariable(String name)
+  {
+    variables.remove(new QName(name));
+  }
+
 }
diff --git a/test/xml/test_xpath_context.rb b/test/xml/test_xpath_context.rb
index aa1d88a55c2..47390cdf1c0 100644
--- a/test/xml/test_xpath_context.rb
+++ b/test/xml/test_xpath_context.rb
@@ -16,19 +16,19 @@ module XML
         xc = XPathContext.new(doc)
 
         assert_raises(XPath::SyntaxError) do
-          xc.evaluate("//xmlns:child")
+          xc.evaluate("//foo:child")
         end
 
-        xc.register_namespaces({ "xmlns" => "http://nokogiri.org/default" })
+        xc.register_namespaces({ "foo" => "http://nokogiri.org/default" })
         assert_pattern do
-          xc.evaluate("//xmlns:child") => [
+          xc.evaluate("//foo:child") => [
             { name: "child", namespace: { href: "http://nokogiri.org/default" } }
           ]
         end
 
-        xc.register_namespaces({ "xmlns" => nil })
+        xc.register_namespaces({ "foo" => nil })
         assert_raises(XPath::SyntaxError) do
-          xc.evaluate("//xmlns:child")
+          xc.evaluate("//foo:child")
         end
       end