diff --git a/src/main/java/com/knecon/fforesight/keycloakcommons/security/TenantAuthenticationManagerResolver.java b/src/main/java/com/knecon/fforesight/keycloakcommons/security/TenantAuthenticationManagerResolver.java
index 2d727b0..56464ae 100644
--- a/src/main/java/com/knecon/fforesight/keycloakcommons/security/TenantAuthenticationManagerResolver.java
+++ b/src/main/java/com/knecon/fforesight/keycloakcommons/security/TenantAuthenticationManagerResolver.java
@@ -3,6 +3,7 @@ package com.knecon.fforesight.keycloakcommons.security;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
 
 import org.springframework.security.authentication.AuthenticationManager;
 import org.springframework.security.authentication.AuthenticationManagerResolver;
@@ -25,7 +26,7 @@ public class TenantAuthenticationManagerResolver implements AuthenticationManage
     private final BearerTokenResolver resolver = new DefaultBearerTokenResolver();
     private final TenantProvider tenantProvider;
 
-    private final Map<String, AuthenticationManager> authenticationManagers = new HashMap<>();
+    private final Map<String, AuthenticationManager> authenticationManagers = new ConcurrentHashMap<>();
 
 
     @Override