diff --git a/core/src/main/java/hudson/security/LDAPSecurityRealm.java b/core/src/main/java/hudson/security/LDAPSecurityRealm.java
index e76f43c..fbe5188 100644
--- a/core/src/main/java/hudson/security/LDAPSecurityRealm.java
+++ b/core/src/main/java/hudson/security/LDAPSecurityRealm.java
@@ -54,6 +54,7 @@ import org.acegisecurity.userdetails.UsernameNotFoundException;
 import org.acegisecurity.userdetails.ldap.LdapUserDetails;
 import org.acegisecurity.userdetails.ldap.LdapUserDetailsImpl;
 import org.apache.commons.collections.map.LRUMap;
+import org.apache.commons.io.input.AutoCloseInputStream;
 import org.kohsuke.stapler.DataBoundConstructor;
 import org.kohsuke.stapler.QueryParameter;
 import org.springframework.dao.DataAccessException;
@@ -66,6 +67,9 @@ import javax.naming.directory.Attributes;
 import javax.naming.directory.BasicAttributes;
 import javax.naming.directory.DirContext;
 import javax.naming.directory.InitialDirContext;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.net.InetAddress;
 import java.net.Socket;
@@ -349,7 +353,15 @@ public class LDAPSecurityRealm extends AbstractPasswordBasedSecurityRealm {
         binding.setVariable("instance", this);
 
         BeanBuilder builder = new BeanBuilder();
-        builder.parse(Jenkins.getInstance().servletContext.getResourceAsStream("/WEB-INF/security/LDAPBindSecurityRealm.groovy"),binding);
+        String fileName = "LDAPBindSecurityRealm.groovy";
+        try {
+            File override = new File(Jenkins.getInstance().getRootDir(), fileName);
+            builder.parse(
+                    override.exists() ? new AutoCloseInputStream(new FileInputStream(override)) :
+                    Jenkins.getInstance().servletContext.getResourceAsStream("/WEB-INF/security/"+ fileName),binding);
+        } catch (FileNotFoundException e) {
+            throw new Error("Failed to load "+fileName,e);
+        }
         WebApplicationContext appContext = builder.createApplicationContext();
 
         ldapTemplate = new LdapTemplate(findBean(InitialDirContextFactory.class, appContext));