diff --git a/src/org/nwapw/abacus/Abacus.java b/src/org/nwapw/abacus/Abacus.java
index 4d50e38..3343d71 100644
--- a/src/org/nwapw/abacus/Abacus.java
+++ b/src/org/nwapw/abacus/Abacus.java
@@ -2,6 +2,7 @@ package org.nwapw.abacus;
 
 import org.nwapw.abacus.plugin.PluginManager;
 //import org.nwapw.abacus.plugin.StandardPlugin;
+import org.nwapw.abacus.plugin.StandardPlugin;
 import org.nwapw.abacus.window.Window;
 import org.nwapw.abacus.plugin.ClassFinder;
 
@@ -25,6 +26,7 @@ public class Abacus {
             e.printStackTrace();
         }
         manager = new PluginManager();
+        manager.addInstantiated(new StandardPlugin(manager));
         try {
             ClassFinder.loadJars("plugins")
                     .forEach(plugin -> manager.addClass(plugin));
diff --git a/src/org/nwapw/abacus/plugin/PluginManager.java b/src/org/nwapw/abacus/plugin/PluginManager.java
index 62b8bb1..8bb3879 100644
--- a/src/org/nwapw/abacus/plugin/PluginManager.java
+++ b/src/org/nwapw/abacus/plugin/PluginManager.java
@@ -12,10 +12,14 @@ import java.util.*;
  */
 public class PluginManager {
 
+    /**
+     * List of classes loaded by this manager.
+     */
+    private Set<Class<?>> loadedPluginClasses;
     /**
      * A list of loaded plugins.
      */
-    private List<Plugin> plugins;
+    private Set<Plugin> plugins;
     /**
      * List of functions that have been cached,
      * that is, found in a plugin and returned.
@@ -43,7 +47,8 @@ public class PluginManager {
      * Creates a new plugin manager.
      */
     public PluginManager(){
-        plugins = new ArrayList<>();
+        loadedPluginClasses = new HashSet<>();
+        plugins = new HashSet<>();
         cachedFunctions = new HashMap<>();
         cachedOperators = new HashMap<>();
         allFunctions = new HashSet<>();
@@ -104,7 +109,9 @@ public class PluginManager {
      * @param plugin the plugin to add.
      */
     public void addInstantiated(Plugin plugin){
+        if(loadedPluginClasses.contains(plugin.getClass())) return;
         plugins.add(plugin);
+        loadedPluginClasses.add(plugin.getClass());
     }
 
     /**