diff --git a/core/src/main/java/org/springframework/ldap/filter/CompareFilter.java b/core/src/main/java/org/springframework/ldap/filter/CompareFilter.java
index e0d1cfe5..97dfd9e8 100644
--- a/core/src/main/java/org/springframework/ldap/filter/CompareFilter.java
+++ b/core/src/main/java/org/springframework/ldap/filter/CompareFilter.java
@@ -87,16 +87,18 @@ public abstract class CompareFilter extends AbstractFilter {
 	 * @see org.springframework.ldap.filter.Filter#equals(java.lang.Object)
 	 */
 	public boolean equals(Object o) {
-		if (o instanceof CompareFilter && o.getClass() == this.getClass()) {
-			CompareFilter that = (CompareFilter) o;
-			EqualsBuilder builder = new EqualsBuilder();
-			builder.append(this.attribute, that.attribute);
-			builder.append(this.value, that.value);
-			return builder.isEquals();
-		}
-		else {
+		if (o == null) {
 			return false;
 		}
+		if (o == this) {
+			return true;
+		}
+		if (o.getClass() != getClass()) {
+			return false;
+		}
+		CompareFilter f = (CompareFilter) o;
+		EqualsBuilder builder = new EqualsBuilder();
+		return builder.append(this.attribute, f.attribute).append(this.value, f.value).isEquals();
 	}
 
 	/**
diff --git a/core/src/main/java/org/springframework/ldap/filter/HardcodedFilter.java b/core/src/main/java/org/springframework/ldap/filter/HardcodedFilter.java
index 08c66f83..bad4f304 100644
--- a/core/src/main/java/org/springframework/ldap/filter/HardcodedFilter.java
+++ b/core/src/main/java/org/springframework/ldap/filter/HardcodedFilter.java
@@ -77,14 +77,17 @@ public class HardcodedFilter extends AbstractFilter {
 	 * @see java.lang.Object#equals(java.lang.Object)
 	 */
 	public boolean equals(Object o) {
-
-		if (o instanceof HardcodedFilter && o.getClass() == this.getClass()) {
-			HardcodedFilter f = (HardcodedFilter) o;
-			EqualsBuilder builder = new EqualsBuilder().append(this.filter, f.filter);
-			return builder.isEquals();
+		if (o == null) {
+			return false;
 		}
-
-		return false;
+		if (o == this) {
+			return true;
+		}
+		if (o.getClass() != getClass()) {
+			return false;
+		}
+		HardcodedFilter f = (HardcodedFilter) o;
+		return new EqualsBuilder().append(this.filter, f.filter).isEquals();
 	}
 
 	/*
diff --git a/core/src/main/java/org/springframework/ldap/filter/NotFilter.java b/core/src/main/java/org/springframework/ldap/filter/NotFilter.java
index 7fd5b8b5..c0fa3ff0 100644
--- a/core/src/main/java/org/springframework/ldap/filter/NotFilter.java
+++ b/core/src/main/java/org/springframework/ldap/filter/NotFilter.java
@@ -17,6 +17,8 @@
 package org.springframework.ldap.filter;
 
 import org.apache.commons.lang.Validate;
+import org.apache.commons.lang.builder.EqualsBuilder;
+import org.apache.commons.lang.builder.HashCodeBuilder;
 
 /**
  * A filter for 'not'. The following code:
@@ -66,13 +68,17 @@ public class NotFilter extends AbstractFilter {
 	 * @see java.lang.Object#equals(java.lang.Object)
 	 */
 	public boolean equals(Object o) {
-
-		if (o instanceof NotFilter && o.getClass() == this.getClass()) {
-			NotFilter f = (NotFilter) o;
-			return this.filter.equals(f.filter);
+		if (o == null) {
+			return false;
 		}
-
-		return false;
+		if (o == this) {
+			return true;
+		}
+		if (o.getClass() != getClass()) {
+			return false;
+		}
+		NotFilter f = (NotFilter) o;
+		return new EqualsBuilder().append(this.filter, f.filter).isEquals();
 	}
 
 	/*
diff --git a/core/src/main/java/org/springframework/ldap/filter/NotPresentFilter.java b/core/src/main/java/org/springframework/ldap/filter/NotPresentFilter.java
index 4f35c3a9..fe4cad40 100644
--- a/core/src/main/java/org/springframework/ldap/filter/NotPresentFilter.java
+++ b/core/src/main/java/org/springframework/ldap/filter/NotPresentFilter.java
@@ -63,14 +63,17 @@ public class NotPresentFilter extends AbstractFilter {
 	 * @see java.lang.Object#equals(java.lang.Object)
 	 */
 	public boolean equals(Object o) {
-
-		if (o instanceof NotPresentFilter && o.getClass() == this.getClass()) {
-			NotPresentFilter f = (NotPresentFilter) o;
-			EqualsBuilder builder = new EqualsBuilder().append(this.attribute, f.attribute);
-			return builder.isEquals();
+		if (o == null) {
+			return false;
 		}
-
-		return false;
+		if (o == this) {
+			return true;
+		}
+		if (o.getClass() != getClass()) {
+			return false;
+		}
+		NotPresentFilter f = (NotPresentFilter) o;
+		return new EqualsBuilder().append(this.attribute, f.attribute).isEquals();
 	}
 
 	/*
diff --git a/core/src/main/java/org/springframework/ldap/filter/PresentFilter.java b/core/src/main/java/org/springframework/ldap/filter/PresentFilter.java
index 6040f5bb..a15d4d08 100644
--- a/core/src/main/java/org/springframework/ldap/filter/PresentFilter.java
+++ b/core/src/main/java/org/springframework/ldap/filter/PresentFilter.java
@@ -62,14 +62,17 @@ public class PresentFilter extends AbstractFilter {
 	 * @see java.lang.Object#equals(java.lang.Object)
 	 */
 	public boolean equals(Object o) {
-
-		if (o instanceof PresentFilter && o.getClass() == this.getClass()) {
-			PresentFilter f = (PresentFilter) o;
-			EqualsBuilder builder = new EqualsBuilder().append(this.attribute, f.attribute);
-			return builder.isEquals();
+		if (o == null) {
+			return false;
 		}
-
-		return false;
+		if (o == this) {
+			return true;
+		}
+		if (o.getClass() != getClass()) {
+			return false;
+		}
+		PresentFilter f = (PresentFilter) o;
+		return new EqualsBuilder().append(this.attribute, f.attribute).isEquals();
 	}
 
 	/*
diff --git a/core/src/test/java/org/springframework/ldap/filter/GreaterThanOrEqualsFilterTest.java b/core/src/test/java/org/springframework/ldap/filter/GreaterThanOrEqualsFilterTest.java
index 5305d5c0..e2e609cd 100644
--- a/core/src/test/java/org/springframework/ldap/filter/GreaterThanOrEqualsFilterTest.java
+++ b/core/src/test/java/org/springframework/ldap/filter/GreaterThanOrEqualsFilterTest.java
@@ -69,7 +69,6 @@ public class GreaterThanOrEqualsFilterTest extends TestCase {
 		GreaterThanOrEqualsFilter subclassObject = new GreaterThanOrEqualsFilter(attribute, value) {
 		};
 
-        new EqualsTester(originalObject, identicalObject, differentObject,
-                subclassObject);
+		new EqualsTester(originalObject, identicalObject, differentObject, subclassObject);
     }
 }
diff --git a/core/src/test/java/org/springframework/ldap/filter/NotFilterTest.java b/core/src/test/java/org/springframework/ldap/filter/NotFilterTest.java
index 95ae8ae8..b9c84fff 100644
--- a/core/src/test/java/org/springframework/ldap/filter/NotFilterTest.java
+++ b/core/src/test/java/org/springframework/ldap/filter/NotFilterTest.java
@@ -48,5 +48,4 @@ public class NotFilterTest extends TestCase {
         new EqualsTester(originalObject, identicalObject, differentObject,
                 subclassObject);
     }
-
 }