diff --git a/WHATS_NEW_DM b/WHATS_NEW_DM
index dca6df6c6..836d10dd5 100644
--- a/WHATS_NEW_DM
+++ b/WHATS_NEW_DM
@@ -1,5 +1,6 @@
 Version 1.02.40 - 
 ===================================
+  Support udev flags even when udev_sync is disabled or not compiled in.
   Remove 'last_rule' from udev rules: honor ENV{DM_UDEV_DISABLE_OTHER_RULES_FLAG}.
   Add dmsetup --inactive support.
   Add dm_task_query_inactive_table to libdevmapper for kernel driver >= 4.16.
diff --git a/libdm/ioctl/libdm-iface.c b/libdm/ioctl/libdm-iface.c
index 6e6446f6e..0a8cce120 100644
--- a/libdm/ioctl/libdm-iface.c
+++ b/libdm/ioctl/libdm-iface.c
@@ -1548,6 +1548,7 @@ static int _create_and_load_v4(struct dm_task *dmt)
 	task->gid = dmt->gid;
 	task->mode = dmt->mode;
 	/* FIXME: Just for udev_check in dm_task_run. Can we avoid this? */
+	task->event_nr = dmt->event_nr & DM_UDEV_FLAGS_MASK;
 	task->cookie_set = dmt->cookie_set;
 
 	r = dm_task_run(task);
diff --git a/libdm/libdevmapper.h b/libdm/libdevmapper.h
index 598a5f475..c6546a63b 100644
--- a/libdm/libdevmapper.h
+++ b/libdm/libdevmapper.h
@@ -1032,6 +1032,10 @@ void dm_report_field_set_value(struct dm_report_field *field, const void *value,
  * of udev rules we use by decoding the cookie prefix. When doing the
  * notification, we replace the cookie prefix with DM_COOKIE_MAGIC,
  * so we notify the right semaphore.
+ * It is still possible to use cookies for passing the flags to udev
+ * rules even when udev_sync is disabled. The base part of the cookie
+ * will be zero (there's no notification semaphore) and prefix will be
+ * set then. However, having udev_sync enabled is highly recommended.
  */
 #define DM_COOKIE_MAGIC 0x0D4D
 #define DM_UDEV_FLAGS_MASK 0xFFFF0000
@@ -1076,7 +1080,7 @@ void dm_report_field_set_value(struct dm_report_field *field, const void *value,
 int dm_cookie_supported(void);
 
 /*
- * Udev notification functions.
+ * Udev synchronisation functions.
  */
 void dm_udev_set_sync_support(int sync_with_udev);
 int dm_udev_get_sync_support(void);
diff --git a/libdm/libdm-common.c b/libdm/libdm-common.c
index 121f02005..43ef63adb 100644
--- a/libdm/libdm-common.c
+++ b/libdm/libdm-common.c
@@ -886,6 +886,8 @@ int dm_udev_get_sync_support(void)
 
 int dm_task_set_cookie(struct dm_task *dmt, uint32_t *cookie, uint16_t flags)
 {
+	if (dm_cookie_supported())
+		dmt->event_nr = flags << DM_UDEV_FLAGS_SHIFT;
 	*cookie = 0;
 
 	return 1;
@@ -1141,8 +1143,11 @@ int dm_task_set_cookie(struct dm_task *dmt, uint32_t *cookie, uint16_t flags)
 {
 	int semid;
 
+	if (dm_cookie_supported())
+		dmt->event_nr = flags << DM_UDEV_FLAGS_SHIFT;
+
 	if (!dm_udev_get_sync_support()) {
-		dmt->event_nr = *cookie = 0;
+		*cookie = 0;
 		return 1;
 	}
 
@@ -1159,8 +1164,7 @@ int dm_task_set_cookie(struct dm_task *dmt, uint32_t *cookie, uint16_t flags)
 		goto bad;
 	}
 
-	dmt->event_nr = (~DM_UDEV_FLAGS_MASK & *cookie) |
-			(flags << DM_UDEV_FLAGS_SHIFT);
+	dmt->event_nr |= ~DM_UDEV_FLAGS_MASK & *cookie;
 	dmt->cookie_set = 1;
 
 	log_debug("Udev cookie 0x%" PRIx32 " (semid %d) assigned to dm_task "
diff --git a/libdm/libdm-deptree.c b/libdm/libdm-deptree.c
index c98fb3474..1465fd345 100644
--- a/libdm/libdm-deptree.c
+++ b/libdm/libdm-deptree.c
@@ -1039,7 +1039,7 @@ int dm_tree_deactivate_children(struct dm_tree_node *dnode,
 			continue;
 
 		if (!_deactivate_node(name, info.major, info.minor,
-				      &dnode->dtree->cookie, dnode->udev_flags)) {
+				      &child->dtree->cookie, child->udev_flags)) {
 			log_error("Unable to deactivate %s (%" PRIu32
 				  ":%" PRIu32 ")", name, info.major,
 				  info.minor);
diff --git a/tools/dmsetup.c b/tools/dmsetup.c
index 186f8f0c3..888edffb1 100644
--- a/tools/dmsetup.c
+++ b/tools/dmsetup.c
@@ -843,9 +843,17 @@ static int _udevcomplete(int argc, char **argv, void *data __attribute((unused))
 	if (!(cookie = _get_cookie_value(argv[1])))
 		return 0;
 
-	/* strip flags from the cookie and use cookie magic instead */
-	cookie = (cookie & ~DM_UDEV_FLAGS_MASK) |
-		  (DM_COOKIE_MAGIC << DM_UDEV_FLAGS_SHIFT);
+	/*
+	 * Strip flags from the cookie and use cookie magic instead.
+	 * If the cookie has non-zero prefix and the base is zero then
+	 * this one carries flags to control udev rules only and it is
+	 * not meant to be for notification. Return with success in this
+	 * situation.
+	 */
+	if (!(cookie &= ~DM_UDEV_FLAGS_MASK))
+		return 1;
+
+	cookie |= DM_COOKIE_MAGIC << DM_UDEV_FLAGS_SHIFT;
 
 	return dm_udev_complete(cookie);
 }