diff --git a/cas-client-core/src/main/java/org/jasig/cas/client/validation/AbstractUrlBasedTicketValidator.java b/cas-client-core/src/main/java/org/jasig/cas/client/validation/AbstractUrlBasedTicketValidator.java
index ce51773..04cf55e 100644
--- a/cas-client-core/src/main/java/org/jasig/cas/client/validation/AbstractUrlBasedTicketValidator.java
+++ b/cas-client-core/src/main/java/org/jasig/cas/client/validation/AbstractUrlBasedTicketValidator.java
@@ -97,9 +97,11 @@ public abstract class AbstractUrlBasedTicketValidator implements TicketValidator
                 final String key = (String) entry.getKey();
                 final String value = (String) entry.getValue();
 
-                buffer.append(key);
-                buffer.append("=");
-                buffer.append(value);
+                if (value != null) {
+	                buffer.append(key);
+	                buffer.append("=");
+	                buffer.append(value);
+                }
             }
 
             return buffer.toString();
@@ -113,6 +115,10 @@ public abstract class AbstractUrlBasedTicketValidator implements TicketValidator
      * @return the encoded url, or the original url if "UTF-8" character encoding could not be found.                       
      */
     protected final String encodeUrl(final String url) {
+    	if (url == null) {
+    		return null;
+    	}
+    	
         try {
             return URLEncoder.encode(url, "UTF-8");
         } catch (final UnsupportedEncodingException e) {
diff --git a/cas-client-core/src/main/java/org/jasig/cas/client/validation/Cas20ProxyReceivingTicketValidationFilter.java b/cas-client-core/src/main/java/org/jasig/cas/client/validation/Cas20ProxyReceivingTicketValidationFilter.java
index 1b13675..2a4081b 100644
--- a/cas-client-core/src/main/java/org/jasig/cas/client/validation/Cas20ProxyReceivingTicketValidationFilter.java
+++ b/cas-client-core/src/main/java/org/jasig/cas/client/validation/Cas20ProxyReceivingTicketValidationFilter.java
@@ -55,7 +55,7 @@ public final class Cas20ProxyReceivingTicketValidationFilter extends AbstractTic
 
     public void init() {
         super.init();
-        CommonUtils.assertNotNull(this.proxyReceptorUrl, "proxyReceptorUrl cannot be null.");
+//        CommonUtils.assertNotNull(this.proxyReceptorUrl, "proxyReceptorUrl cannot be null.");
         CommonUtils.assertNotNull(this.proxyGrantingTicketStorage, "proxyGrantingTicketStorage cannot be null.");
     }
 
@@ -106,7 +106,7 @@ public final class Cas20ProxyReceivingTicketValidationFilter extends AbstractTic
         final HttpServletResponse response = (HttpServletResponse) servletResponse;
         final String requestUri = request.getRequestURI();
 
-        if (!requestUri.endsWith(proxyReceptorUrl)) {
+        if (CommonUtils.isEmpty(this.proxyReceptorUrl) || !requestUri.endsWith(this.proxyReceptorUrl)) {
             return true;
         }