diff --git a/src/main/java/net/openhft/chronicle/map/MapClosable.java b/src/main/java/net/openhft/chronicle/map/MapClosable.java
index dfc5dc9c0..d775ea379 100644
--- a/src/main/java/net/openhft/chronicle/map/MapClosable.java
+++ b/src/main/java/net/openhft/chronicle/map/MapClosable.java
@@ -6,6 +6,7 @@ public interface MapClosable extends Closeable {
 
     @Override
     default boolean isClosed() {
-        throw new UnsupportedOperationException();
+        // if we don't know, pretend it is not.
+        return false;
     }
 }