diff --git a/transport/src/main/java/io/netty/channel/nio/AbstractNioChannel.java b/transport/src/main/java/io/netty/channel/nio/AbstractNioChannel.java
index 7a33133b63..582e6ae6fa 100644
--- a/transport/src/main/java/io/netty/channel/nio/AbstractNioChannel.java
+++ b/transport/src/main/java/io/netty/channel/nio/AbstractNioChannel.java
@@ -159,7 +159,10 @@ public abstract class AbstractNioChannel extends AbstractChannel {
                 });
             }
         } else {
-            setReadPending0(readPending);
+            // Best effort if we are not registered yet clear readPending.
+            // NB: We only set the boolean field instead of calling clearReadPending0(), because the SelectionKey is
+            // not set yet so it would produce an assertion failure.
+            this.readPending = readPending;
         }
     }