diff --git a/r2dbc-mysql/src/main/java/io/asyncer/r2dbc/mysql/MySqlConnectionConfiguration.java b/r2dbc-mysql/src/main/java/io/asyncer/r2dbc/mysql/MySqlConnectionConfiguration.java
index ef49895ae..60f22e816 100644
--- a/r2dbc-mysql/src/main/java/io/asyncer/r2dbc/mysql/MySqlConnectionConfiguration.java
+++ b/r2dbc-mysql/src/main/java/io/asyncer/r2dbc/mysql/MySqlConnectionConfiguration.java
@@ -128,6 +128,7 @@ public final class MySqlConnectionConfiguration {
     @Nullable
     private final Publisher<String> passwordPublisher;
 
+    @Nullable
     private final AddressResolverGroup<?> resolver;
 
     private MySqlConnectionConfiguration(