diff --git a/sys/dev/null/null.c b/sys/dev/null/null.c
--- a/sys/dev/null/null.c
+++ b/sys/dev/null/null.c
@@ -4,6 +4,7 @@
  * Copyright (c) 2000 Mark R. V. Murray & Jeroen C. van Gelderen
  * Copyright (c) 2001-2004 Mark R. V. Murray
  * Copyright (c) 2014 Eitan Adler
+ * Copyright (c) 2025 Pietro Cerutti
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -39,6 +40,7 @@
 #include <sys/disk.h>
 #include <sys/bus.h>
 #include <sys/filio.h>
+#include <sys/event.h>
 
 #include <machine/bus.h>
 #include <machine/vmparam.h>
@@ -48,18 +50,30 @@
 static struct cdev *null_dev;
 static struct cdev *zero_dev;
 
+#define FULL_NAME "full"
+#define NULL_NAME "null"
+#define ZERO_NAME "zero"
+
 static d_write_t full_write;
 static d_write_t null_write;
 static d_ioctl_t null_ioctl;
 static d_ioctl_t zero_ioctl;
 static d_read_t zero_read;
+static d_kqfilter_t null_kqfilter;
+static int immediate_event(struct knote *kn, long hint);
+
+static const struct filterops immediate_filterops = {
+	.f_isfd =	1,
+	.f_event =	immediate_event
+};
 
 static struct cdevsw full_cdevsw = {
 	.d_version =	D_VERSION,
 	.d_read =	zero_read,
 	.d_write =	full_write,
 	.d_ioctl =	zero_ioctl,
-	.d_name =	"full",
+	.d_kqfilter =	null_kqfilter,
+	.d_name =	FULL_NAME,
 };
 
 static struct cdevsw null_cdevsw = {
@@ -67,7 +81,8 @@
 	.d_read =	(d_read_t *)nullop,
 	.d_write =	null_write,
 	.d_ioctl =	null_ioctl,
-	.d_name =	"null",
+	.d_kqfilter =	null_kqfilter,
+	.d_name =	NULL_NAME,
 };
 
 static struct cdevsw zero_cdevsw = {
@@ -75,7 +90,8 @@
 	.d_read =	zero_read,
 	.d_write =	null_write,
 	.d_ioctl =	zero_ioctl,
-	.d_name =	"zero",
+	.d_kqfilter =	null_kqfilter,
+	.d_name =	ZERO_NAME,
 	.d_flags =	D_MMAP_ANON,
 };
 
@@ -174,11 +190,11 @@
 		if (bootverbose)
 			printf("null: <full device, null device, zero device>\n");
 		full_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &full_cdevsw, 0,
-		    NULL, UID_ROOT, GID_WHEEL, 0666, "full");
+		    NULL, UID_ROOT, GID_WHEEL, 0666, FULL_NAME);
 		null_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &null_cdevsw, 0,
-		    NULL, UID_ROOT, GID_WHEEL, 0666, "null");
+		    NULL, UID_ROOT, GID_WHEEL, 0666, NULL_NAME);
 		zero_dev = make_dev_credf(MAKEDEV_ETERNAL_KLD, &zero_cdevsw, 0,
-		    NULL, UID_ROOT, GID_WHEEL, 0666, "zero");
+		    NULL, UID_ROOT, GID_WHEEL, 0666, ZERO_NAME);
 		break;
 
 	case MOD_UNLOAD:
@@ -197,5 +213,25 @@
 	return (0);
 }
 
+static int
+immediate_event(struct knote *kn, long hint)
+{
+	return 1;
+}
+
+static int
+null_kqfilter(struct cdev *dev, struct knote *kn)
+{
+	switch (kn->kn_filter)
+	{
+	case EVFILT_READ:
+	case EVFILT_WRITE:
+	    kn->kn_fop = &immediate_filterops;
+	    return (0);
+	default:
+	    return(EOPNOTSUPP);
+	}
+}
+
 DEV_MODULE(null, null_modevent, NULL);
 MODULE_VERSION(null, 1);