diff --git a/spring-binding/src/main/java/org/springframework/binding/method/MethodKey.java b/spring-binding/src/main/java/org/springframework/binding/method/MethodKey.java
index b5ec5d55..01ee2b1f 100644
--- a/spring-binding/src/main/java/org/springframework/binding/method/MethodKey.java
+++ b/spring-binding/src/main/java/org/springframework/binding/method/MethodKey.java
@@ -42,7 +42,9 @@ public class MethodKey implements Serializable {
 	private String methodName;
 
 	/**
-	 * The method's actual parameter types.
+	 * The method's actual parameter types. Could contain null values
+	 * if the user did not specify a parameter type for the corresponding
+	 * parameter
 	 */
 	private Class[] parameterTypes;
 
@@ -81,7 +83,8 @@ public class MethodKey implements Serializable {
 	}
 
 	/**
-	 * Returns the method parameter types.
+	 * Returns the method parameter types. Could contain null values
+	 * if no type was specified for the corresponding parameter.
 	 */
 	public Class[] getParameterTypes() {
 		return parameterTypes;
@@ -104,7 +107,7 @@ public class MethodKey implements Serializable {
 	 */
 	protected Method resolveMethod() throws InvalidMethodKeyException {
 		try {
-			return declaredType.getMethod(methodName, getParameterTypes());
+			return declaredType.getMethod(methodName, parameterTypes);
 		}
 		catch (NoSuchMethodException e) {
 			Method method = findMethodConsiderAssignableParameterTypes();
@@ -126,7 +129,7 @@ public class MethodKey implements Serializable {
 			if (candidateMethods[i].getName().equals(methodName)) {
 				// Check if the method has the correct number of parameters.
 				Class[] candidateParameterTypes = candidateMethods[i].getParameterTypes();
-				if (candidateParameterTypes.length == getParameterTypes().length) {
+				if (candidateParameterTypes.length == parameterTypes.length) {
 					int numberOfCorrectArguments = 0;
 					for (int j = 0; j < candidateParameterTypes.length; j++) {
 						// Check if the candidate type is assignable to the sig
@@ -139,8 +142,7 @@ public class MethodKey implements Serializable {
 							}
 						}
 						else {
-							// just match on a null param type (effectively
-							// 'any')
+							// just match on a null param type (effectively 'any')
 							numberOfCorrectArguments++;
 						}
 					}
@@ -240,7 +242,12 @@ public class MethodKey implements Serializable {
 	private String parameterTypesString() {
 		StringBuffer parameterTypesString = new StringBuffer();
 		for (int i = 0; i < parameterTypes.length; i++) {
-			parameterTypesString.append(ClassUtils.getShortName(parameterTypes[i]));
+			if (parameterTypes[i] == null) {
+				parameterTypesString.append("<any>");
+			}
+			else {
+				parameterTypesString.append(ClassUtils.getShortName(parameterTypes[i]));
+			}
 			if (i < parameterTypes.length - 1) {
 				parameterTypesString.append(',');
 			}
diff --git a/spring-binding/src/main/java/org/springframework/binding/method/Parameter.java b/spring-binding/src/main/java/org/springframework/binding/method/Parameter.java
index a6fd496a..3c16483c 100644
--- a/spring-binding/src/main/java/org/springframework/binding/method/Parameter.java
+++ b/spring-binding/src/main/java/org/springframework/binding/method/Parameter.java
@@ -45,7 +45,7 @@ public class Parameter implements Serializable {
 	/**
 	 * Create a new named parameter definition.  Named parameters are capable of resolving 
 	 * parameter values (arguments) from argument sources.
-	 * @param type the type the parameter type, may be null
+	 * @param type the parameter type, may be null
 	 * @param name the name the method argument expression (required)
 	 */
 	public Parameter(Class type, Expression name) {
@@ -55,7 +55,8 @@ public class Parameter implements Serializable {
 	}
 
 	/**
-	 * Returns the parameter type.
+	 * Returns the parameter type. Could be null if no parameter type
+	 * was specified.
 	 */
 	public Class getType() {
 		return type;
diff --git a/spring-binding/src/main/java/org/springframework/binding/method/Parameters.java b/spring-binding/src/main/java/org/springframework/binding/method/Parameters.java
index 1eca2776..1c636881 100644
--- a/spring-binding/src/main/java/org/springframework/binding/method/Parameters.java
+++ b/spring-binding/src/main/java/org/springframework/binding/method/Parameters.java
@@ -96,7 +96,9 @@ public class Parameters implements Serializable {
 	}
 
 	/**
-	 * Get an array containing each parameter type.
+	 * Get an array containing each parameter type. The resulting array
+	 * could contain null values if the corresponding parameters did
+	 * not specify a parameter type.
 	 * @return the types
 	 */
 	public Class[] getTypesArray() {
diff --git a/spring-webflow/changelog.txt b/spring-webflow/changelog.txt
index 80d1fd3a..a0b65ce9 100644
--- a/spring-webflow/changelog.txt
+++ b/spring-webflow/changelog.txt
@@ -7,7 +7,8 @@ Changes in version 1.0.2 ()
 
 Package org.springframework.binding
 * GenericConversionService.getConversionExecutor() now uses isAssignableFrom to detect situations
-  where no conversion is necessary (SWF-264). 
+  where no conversion is necessary (SWF-264).
+* Fixed possbile NullPointerException in parameterTypesString() (SWF-265).
 
 Package org.springframework.webflow.action
 * FormAction methods doBind() and createBinder() now declare "throws Exception".
diff --git a/spring-webflow/src/main/java/org/springframework/webflow/engine/ActionExecutor.java b/spring-webflow/src/main/java/org/springframework/webflow/engine/ActionExecutor.java
index 4c493130..5744c7cb 100644
--- a/spring-webflow/src/main/java/org/springframework/webflow/engine/ActionExecutor.java
+++ b/spring-webflow/src/main/java/org/springframework/webflow/engine/ActionExecutor.java
@@ -64,7 +64,7 @@ public class ActionExecutor {
 			throw e;
 		}
 		catch (Exception e) {
-			// wrap the action as an ActionExecutionException
+			// wrap the exception as an ActionExecutionException
 			throw new ActionExecutionException(context.getActiveFlow().getId(),
 					context.getCurrentState() != null ? context.getCurrentState().getId() : null, action, context
 							.getAttributes(), e);