diff --git a/src/main/java/com/zaxxer/hikari/proxy/ConnectionProxy.java b/src/main/java/com/zaxxer/hikari/proxy/ConnectionProxy.java
index 445328f7..ce3034de 100644
--- a/src/main/java/com/zaxxer/hikari/proxy/ConnectionProxy.java
+++ b/src/main/java/com/zaxxer/hikari/proxy/ConnectionProxy.java
@@ -58,7 +58,7 @@ public abstract class ConnectionProxy implements IHikariConnectionProxy
     private boolean forceClose;
     private boolean isAutoCommitDirty;
     private boolean isCatalogDirty;
-    private boolean isClosed;
+    private volatile boolean isClosed;
     private boolean isReadOnlyDirty;
     private boolean isTransactionIsolationDirty;
     private volatile long lastAccess;