diff --git a/httpcore5/src/main/java/org/apache/hc/core5/reactor/IOSessionImpl.java b/httpcore5/src/main/java/org/apache/hc/core5/reactor/IOSessionImpl.java
index 8622c50a7..03de8716b 100644
--- a/httpcore5/src/main/java/org/apache/hc/core5/reactor/IOSessionImpl.java
+++ b/httpcore5/src/main/java/org/apache/hc/core5/reactor/IOSessionImpl.java
@@ -171,6 +171,9 @@ public SocketAddress getRemoteAddress() {
 
     @Override
     public int getEventMask() {
+        if (isStatusClosed()) {
+            return 0;
+        }
         return this.key.interestOps();
     }
 
diff --git a/httpcore5/src/test/java/org/apache/hc/core5/reactor/TestIOSessionImpl.java b/httpcore5/src/test/java/org/apache/hc/core5/reactor/TestIOSessionImpl.java
index 92ed454ab..d92c14d6a 100644
--- a/httpcore5/src/test/java/org/apache/hc/core5/reactor/TestIOSessionImpl.java
+++ b/httpcore5/src/test/java/org/apache/hc/core5/reactor/TestIOSessionImpl.java
@@ -246,6 +246,20 @@ void eventMaskHelpersWork() throws Exception {
         }
     }
 
+    @Test
+    @SuppressWarnings("resource")
+    void eventMaskIsEmptyOnceClosed() throws Exception {
+        try (Selector selector = Selector.open();
+             SocketChannel channel = SocketChannel.open()) {
+            channel.configureBlocking(false);
+            final SelectionKey key = channel.register(selector, SelectionKey.OP_READ);
+            final IOSessionImpl session = new IOSessionImpl("t", key, channel, null);
+            session.close(CloseMode.IMMEDIATE);
+
+            Assertions.assertEquals(0, session.getEventMask());
+        }
+    }
+
     @Test
     @SuppressWarnings("resource")
     void toStringIncludesStatus() throws Exception {