diff --git a/spring-webflow/src/main/java/org/springframework/webflow/mvc/builder/FlowResourceFlowViewResolver.java b/spring-webflow/src/main/java/org/springframework/webflow/mvc/builder/FlowResourceFlowViewResolver.java
index da0f9923..2f136567 100644
--- a/spring-webflow/src/main/java/org/springframework/webflow/mvc/builder/FlowResourceFlowViewResolver.java
+++ b/spring-webflow/src/main/java/org/springframework/webflow/mvc/builder/FlowResourceFlowViewResolver.java
@@ -35,7 +35,7 @@ import org.springframework.webflow.mvc.view.FlowViewResolver;
  */
 public class FlowResourceFlowViewResolver implements FlowViewResolver {
 
-	private static final boolean JSTL_PRESENT = ClassUtils.isPresent("javax.servlet.jsp.jstl.fmt.LocalizationContext");
+	private static final boolean JSTL_PRESENT = ClassUtils.isPresent("javax.servlet.jsp.jstl.fmt.LocalizationContext", FlowResourceFlowViewResolver.class.getClassLoader());
 
 	private String defaultViewSuffix = ".jsp";
 
diff --git a/spring-webflow/src/main/java/org/springframework/webflow/mvc/builder/MvcEnvironment.java b/spring-webflow/src/main/java/org/springframework/webflow/mvc/builder/MvcEnvironment.java
index a2de6d0c..d5c9db86 100644
--- a/spring-webflow/src/main/java/org/springframework/webflow/mvc/builder/MvcEnvironment.java
+++ b/spring-webflow/src/main/java/org/springframework/webflow/mvc/builder/MvcEnvironment.java
@@ -43,7 +43,7 @@ public enum MvcEnvironment {
 	 * @return the web environment the context is running in, or null if not running in a web environment
 	 */
 	public static MvcEnvironment environmentFor(ApplicationContext applicationContext) {
-		if (ClassUtils.isPresent("javax.portlet.PortletContext") && isPortletApplicationContext(applicationContext)) {
+		if (ClassUtils.isPresent("javax.portlet.PortletContext", MvcEnvironment.class.getClassLoader()) && isPortletApplicationContext(applicationContext)) {
 			return MvcEnvironment.PORTLET;
 		} else if (applicationContext instanceof WebApplicationContext) {
 			return MvcEnvironment.SERVLET;
@@ -53,7 +53,7 @@ public enum MvcEnvironment {
 	}
 
 	private static boolean isPortletApplicationContext(ApplicationContext applicationContext) {
-		return ClassUtils.isPresent("org.springframework.web.portlet.context.ConfigurablePortletApplicationContext")
+		return ClassUtils.isPresent("org.springframework.web.portlet.context.ConfigurablePortletApplicationContext", MvcEnvironment.class.getClassLoader())
 				&& applicationContext instanceof ConfigurablePortletApplicationContext;
 	}