diff --git a/hikaricp-common/src/main/java/com/zaxxer/hikari/proxy/ConnectionProxy.java b/hikaricp-common/src/main/java/com/zaxxer/hikari/proxy/ConnectionProxy.java
index <HASH>..<HASH> 100644
--- a/hikaricp-common/src/main/java/com/zaxxer/hikari/proxy/ConnectionProxy.java
+++ b/hikaricp-common/src/main/java/com/zaxxer/hikari/proxy/ConnectionProxy.java
@@ -209,6 +209,13 @@ public abstract class ConnectionProxy implements IHikariConnectionProxy
 
    /** {@inheritDoc} */
    @Override
+   public boolean isClosed() throws SQLException
+   {
+      return (delegate == ClosedConnection.CLOSED_CONNECTION);
+   }
+
+   /** {@inheritDoc} */
+   @Override
    public Statement createStatement() throws SQLException
    {
       return ProxyFactory.getProxyStatement(this, trackStatement(delegate.createStatement()));
Fix #<I> continue to override isClosed() ... we had removed it but it should reflect HikariCP's understanding of the closed state rather than delegating to the driver.