diff --git a/src/main/java/org/hazlewood/connor/bottema/emailaddress/EmailAddressValidator.java b/src/main/java/org/hazlewood/connor/bottema/emailaddress/EmailAddressValidator.java
index a93556f..eb59e05 100644
--- a/src/main/java/org/hazlewood/connor/bottema/emailaddress/EmailAddressValidator.java
+++ b/src/main/java/org/hazlewood/connor/bottema/emailaddress/EmailAddressValidator.java
@@ -119,7 +119,7 @@ private EmailAddressValidator() {
 	 * @see EmailAddressCriteria#DEFAULT
 	 */
 	@SuppressWarnings("unused")
-	public static boolean isValid(final String email) {
+	public static boolean isValid(@Nullable final String email) {
 		return isValid(email, EmailAddressCriteria.DEFAULT);
 	}
 
@@ -131,7 +131,7 @@ public static boolean isValid(final String email) {
 	 * @see EmailAddressCriteria#RFC_COMPLIANT
 	 */
 	@SuppressWarnings("unused")
-	public static boolean isValidStrict(final String email) {
+	public static boolean isValidStrict(@Nullable final String email) {
 		return isValid(email, EmailAddressCriteria.RFC_COMPLIANT);
 	}