diff --git a/WHATS_NEW b/WHATS_NEW
index fbe24180d..5b1494b7f 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
 Version 2.02.178 - 
 =====================================
+  lvconvert: don't return success on degraded -m raid1 conversion
   --enable-testing switch for ./configure has been removed.
   --with-snapshots switch for ./configure has been removed.
   --with-mirrors switch for ./configure has been removed.
diff --git a/lib/metadata/raid_manip.c b/lib/metadata/raid_manip.c
index 7d82a24b8..1b9ebcf94 100644
--- a/lib/metadata/raid_manip.c
+++ b/lib/metadata/raid_manip.c
@@ -3200,6 +3200,27 @@ static int _raid_remove_images(struct logical_volume *lv, int yes,
 	return 1;
 }
 
+/* Check if single SubLV @slv is degraded. */
+static int _sublv_is_degraded(const struct logical_volume *slv)
+{
+	return !slv || lv_is_partial(slv) || lv_is_virtual(slv);
+}
+
+/* Return failed component SubLV count for @lv. */
+static uint32_t _lv_get_nr_failed_components(const struct logical_volume *lv)
+{
+	uint32_t r = 0, s;
+	struct lv_segment *seg = first_seg(lv);
+
+	for (s = 0; s < seg->area_count; s++)
+		if (_sublv_is_degraded(seg_lv(seg, s)) ||
+		    (seg->meta_areas &&
+		     _sublv_is_degraded(seg_metalv(seg, s))))
+			r++;
+
+	return r;
+}
+
 /*
  * _lv_raid_change_image_count
  * new_count: The absolute count of images (e.g. '2' for a 2-way mirror)
@@ -3215,12 +3236,25 @@ static int _lv_raid_change_image_count(struct logical_volume *lv, int yes, uint3
 				       struct dm_list *allocate_pvs, struct dm_list *removal_lvs,
 				       int commit, int use_existing_area_len)
 {
+	int r;
 	uint32_t old_count = lv_raid_image_count(lv);
 
+	/* If there's failed component SubLVs, require repair first! */
+	if (lv_is_raid(lv) &&
+	    _lv_get_nr_failed_components(lv) &&
+	    new_count >= old_count) {
+		log_error("Can't change number of mirrors of degraded %s.",
+			  display_lvname(lv));
+		log_error("Please run \"lvconvert --repair %s\" first.",
+			  display_lvname(lv));
+		r = 0;
+	} else
+		r = 1;
+
 	if (old_count == new_count) {
 		log_warn("WARNING: %s already has image count of %d.",
 			 display_lvname(lv), new_count);
-		return 1;
+		return r;
 	}
 
 	/*
diff --git a/test/shell/lvconvert-m-raid1-degraded.sh b/test/shell/lvconvert-m-raid1-degraded.sh
new file mode 100644
index 000000000..f8a65d962
--- /dev/null
+++ b/test/shell/lvconvert-m-raid1-degraded.sh
@@ -0,0 +1,47 @@
+#!/usr/bin/env bash
+
+# Copyright (C) 2018 Red Hat, Inc. All rights reserved.
+#
+# This copyrighted material is made available to anyone wishing to use,
+# modify, copy, or redistribute it subject to the terms and conditions
+# of the GNU General Public License v.2.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software Foundation,
+# Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+SKIP_WITH_LVMLOCKD=1
+SKIP_WITH_LVMPOLLD=1
+
+. lib/inittest
+
+aux have_raid 1 3 0 || skip
+
+aux lvmconf 'activation/raid_fault_policy = "warn"'
+
+aux prepare_vg 3 32
+get_devs
+
+# Create 2-legged RAID1 and wait for it to complete initial resync
+lvcreate --type raid1 -m 1 -l 4 -n $lv $vg "$dev1" "$dev2"
+aux wait_for_sync $vg $lv
+
+# Disable first PV thus erroring first leg
+aux disable_dev "$dev1"
+
+# Reduce VG by missing PV
+vgreduce --force --removemissing $vg
+check raid_leg_status $vg $lv "DA"
+
+# Conversion to 2 legs must fail on degraded 2-legged raid1 LV
+not lvconvert -y -m1 $vg/$lv
+check raid_leg_status $vg $lv "DA"
+
+# Repair has to succeed
+lvconvert -y --repair $vg/$lv
+aux wait_for_sync $vg $lv
+check raid_leg_status $vg $lv "AA"
+
+lvremove -ff $vg/$lv
+
+vgremove -ff $vg