diff --git a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/AbstractDeclaredTransaction.java b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/AbstractDeclaredTransaction.java
index 898582011..dc6df9e55 100644
--- a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/AbstractDeclaredTransaction.java
+++ b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/AbstractDeclaredTransaction.java
@@ -106,6 +106,9 @@ public abstract class AbstractDeclaredTransaction implements Comparable<IDeclare
    * @see java.lang.Object#equals(java.lang.Object)
    */
   public boolean equals(Object obj) {
+    if (obj == null) {
+      return false;
+    }
     if (this.getClass() != obj.getClass())
       return false;
     AbstractDeclaredTransaction other = (AbstractDeclaredTransaction) obj;
diff --git a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/J2EEUtil.java b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/J2EEUtil.java
index fd0ca73b4..0dfe9458d 100644
--- a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/J2EEUtil.java
+++ b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/J2EEUtil.java
@@ -144,10 +144,14 @@ public class J2EEUtil {
    * 
    * @param method the Method in question
    * @return String a String representation of the signature.
+   * @throws IllegalArgumentException  if method is null
    */
   @SuppressWarnings("unchecked")
   public static String buildDescriptor(Method method) {
 
+    if (method == null) {
+      throw new IllegalArgumentException("method is null");
+    }
     StringBuffer sb = new StringBuffer();
 
     sb.append("(");
diff --git a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/ClassImpl.java b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/ClassImpl.java
index 4a022af4a..0141a4825 100644
--- a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/ClassImpl.java
+++ b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/ClassImpl.java
@@ -81,6 +81,9 @@ public class ClassImpl implements IClass {
    * @see java.lang.Object#equals(java.lang.Object)
    */
   public boolean equals(Object arg0) {
+    if (arg0 == null) {
+      return false;
+    }
     if (getClass().equals(arg0.getClass())) {
       ClassImpl other = (ClassImpl) arg0;
       return getName().equals(other.getName()) && getClassLoaderName().equals(other.getClassLoaderName());
diff --git a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/FieldImpl.java b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/FieldImpl.java
index 6caff7d8e..2f689aadf 100644
--- a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/FieldImpl.java
+++ b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/FieldImpl.java
@@ -37,6 +37,9 @@ public class FieldImpl extends MemberImpl implements IField {
    * @see com.ibm.wala.j2ee.client.impl.MemberImpl#equals(java.lang.Object)
    */
   public boolean equals(Object arg0) {
+    if (arg0 == null) {
+      return false;
+    }
     if (getClass().equals(arg0.getClass())) {
       FieldImpl other = (FieldImpl)arg0;
       return getName().equals(other.getName()) && getClassLoaderName().equals(other.getClassLoaderName());
diff --git a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/MethodImpl.java b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/MethodImpl.java
index 1625e9c6e..cc4b077ab 100644
--- a/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/MethodImpl.java
+++ b/com.ibm.wala.j2ee/src/com/ibm/wala/j2ee/client/impl/MethodImpl.java
@@ -63,6 +63,9 @@ public class MethodImpl extends MemberImpl implements IMethod {
    * @see java.lang.Object#equals(java.lang.Object)
    */
   public boolean equals(Object arg0) {
+    if (arg0 == null) {
+      return false;
+    }
     if (getClass().equals(arg0.getClass())) {
       MethodImpl other = (MethodImpl) arg0;
       return getDeclaringClass().equals(other.getDeclaringClass()) && getClassLoaderName().equals(other.getClassLoaderName())