diff --git a/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java b/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
index 8d54297f..9589014a 100644
--- a/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
+++ b/src/main/java/org/bukkit/plugin/java/JavaPluginLoader.java
@@ -12,6 +12,7 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
@@ -48,7 +49,7 @@ import org.yaml.snakeyaml.error.YAMLException;
 public final class JavaPluginLoader implements PluginLoader {
     final Server server;
     private final Pattern[] fileFilters = new Pattern[] { Pattern.compile("\\.jar$"), };
-    private final Map<String, Class<?>> classes = new HashMap<String, Class<?>>();
+    private final Map<String, Class<?>> classes = new ConcurrentHashMap<String, Class<?>>();
     private final List<PluginClassLoader> loaders = new CopyOnWriteArrayList<PluginClassLoader>();
 
     /**
diff --git a/src/main/java/org/bukkit/plugin/java/PluginClassLoader.java b/src/main/java/org/bukkit/plugin/java/PluginClassLoader.java
index 154481af..7a8abe75 100644
--- a/src/main/java/org/bukkit/plugin/java/PluginClassLoader.java
+++ b/src/main/java/org/bukkit/plugin/java/PluginClassLoader.java
@@ -9,9 +9,9 @@ import java.net.URL;
 import java.net.URLClassLoader;
 import java.security.CodeSigner;
 import java.security.CodeSource;
-import java.util.HashMap;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 import java.util.jar.Manifest;
@@ -25,7 +25,7 @@ import org.bukkit.plugin.PluginDescriptionFile;
  */
 final class PluginClassLoader extends URLClassLoader {
     private final JavaPluginLoader loader;
-    private final Map<String, Class<?>> classes = new HashMap<String, Class<?>>();
+    private final Map<String, Class<?>> classes = new ConcurrentHashMap<String, Class<?>>();
     private final PluginDescriptionFile description;
     private final File dataFolder;
     private final File file;
@@ -36,6 +36,10 @@ final class PluginClassLoader extends URLClassLoader {
     private JavaPlugin pluginInit;
     private IllegalStateException pluginState;
 
+    static {
+        ClassLoader.registerAsParallelCapable();
+    }
+
     PluginClassLoader(final JavaPluginLoader loader, final ClassLoader parent, final PluginDescriptionFile description, final File dataFolder, final File file) throws IOException, InvalidPluginException, MalformedURLException {
         super(new URL[] {file.toURI().toURL()}, parent);
         Validate.notNull(loader, "Loader cannot be null");