diff --git a/src/main/java/fr/xephi/authme/process/login/AsynchronousLogin.java b/src/main/java/fr/xephi/authme/process/login/AsynchronousLogin.java
index 9a32a92f..b9ebbdb7 100644
--- a/src/main/java/fr/xephi/authme/process/login/AsynchronousLogin.java
+++ b/src/main/java/fr/xephi/authme/process/login/AsynchronousLogin.java
@@ -112,7 +112,7 @@ public class AsynchronousLogin implements AsynchronousProcess {
      *
      * @param player the player to log in
      */
-    public void forceLogin(Player player) {
+    public synchronized void forceLogin(Player player) {
         PlayerAuth auth = getPlayerAuth(player);
         if (auth != null) {
             performLogin(player, auth);
diff --git a/src/main/java/fr/xephi/authme/process/register/AsyncRegister.java b/src/main/java/fr/xephi/authme/process/register/AsyncRegister.java
index f5fe3be6..a13bcf3c 100644
--- a/src/main/java/fr/xephi/authme/process/register/AsyncRegister.java
+++ b/src/main/java/fr/xephi/authme/process/register/AsyncRegister.java
@@ -50,7 +50,7 @@ public class AsyncRegister implements AsynchronousProcess {
      * @param parameters the parameters
      * @param <P>        parameters type
      */
-    public <P extends RegistrationParameters> void register(RegistrationMethod<P> variant, P parameters) {
+    public synchronized <P extends RegistrationParameters> void register(RegistrationMethod<P> variant, P parameters) {
         if (preRegisterCheck(variant, parameters.getPlayer())) {
             RegistrationExecutor<P> executor = registrationExecutorFactory.getSingleton(variant.getExecutorClass());
             if (executor.isRegistrationAdmitted(parameters)) {