diff --git a/WHATS_NEW b/WHATS_NEW
index 17516000b..b6f2936d6 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,8 +1,8 @@
 Version 2.00.23 - 
 ====================================
+  Test for incompatible format/segtype combinations in lv_extend.
   Fix lvchange example on man page.
 
-
 Version 2.00.22 - 3rd September 2004
 ====================================
   Fix /dev/vgname perms.
diff --git a/lib/format1/format1.c b/lib/format1/format1.c
index cd47b56ce..b1db3e81f 100644
--- a/lib/format1/format1.c
+++ b/lib/format1/format1.c
@@ -24,6 +24,7 @@
 #include "lvmcache.h"
 #include "lvm1-label.h"
 #include "format1.h"
+#include "segtypes.h"
 
 #define FMT_LVM1_NAME "lvm1"
 
@@ -492,6 +493,17 @@ static int _vg_setup(struct format_instance *fid, struct volume_group *vg)
 	return 1;
 }
 
+static int _segtype_supported (struct format_instance *fid, 
+			       struct segment_type *segtype)
+{
+	if (!(segtype->flags & SEG_FORMAT1_SUPPORT)) {
+		stack;
+		return 0;
+	}
+
+	return 1;
+}
+
 static struct metadata_area_ops _metadata_format1_ops = {
 	vg_read:_vg_read,
 	vg_write:_vg_write,
@@ -542,6 +554,7 @@ static struct format_handler _format1_ops = {
 	pv_write:_pv_write,
 	lv_setup:_lv_setup,
 	vg_setup:_vg_setup,
+	segtype_supported:_segtype_supported,
 	create_instance:_create_instance,
 	destroy_instance:_destroy_instance,
 	destroy:_destroy,
diff --git a/lib/metadata/lv_manip.c b/lib/metadata/lv_manip.c
index 3fc3d985d..8d649b5fd 100644
--- a/lib/metadata/lv_manip.c
+++ b/lib/metadata/lv_manip.c
@@ -623,6 +623,16 @@ int lv_extend(struct format_instance *fid,
 	lv->le_count += extents;
 	lv->size += (uint64_t) extents *lv->vg->extent_size;
 
+	if (fid->fmt->ops->segtype_supported &&
+	    !fid->fmt->ops->segtype_supported(fid, segtype)) {
+		log_error("Metadata format (%s) does not support required "
+			  "LV segment type (%s).", fid->fmt->name,
+			  segtype->name);
+		log_error("Consider changing the metadata format by running "
+			  "vgconvert.");
+		return 0;
+	}
+
 	if (!_allocate(lv->vg, lv, allocatable_pvs, old_le_count, alloc,
 		       segtype, stripes, stripe_size, mirrors, mirrored_pv,
 		       mirrored_pe, status)) {
diff --git a/lib/metadata/metadata.h b/lib/metadata/metadata.h
index 2022130b8..c30952dd4 100644
--- a/lib/metadata/metadata.h
+++ b/lib/metadata/metadata.h
@@ -341,6 +341,12 @@ struct format_handler {
 	 */
 	int (*vg_setup) (struct format_instance * fi, struct volume_group * vg);
 
+	/*
+	 * Check whether particular segment type is supported.
+	 */
+	int (*segtype_supported) (struct format_instance *fid,
+				  struct segment_type *segtype);
+
 	/*
 	 * Create format instance with a particular metadata area
 	 */
diff --git a/lib/metadata/mirror.c b/lib/metadata/mirror.c
index 7664c7eb3..cf76dea0b 100644
--- a/lib/metadata/mirror.c
+++ b/lib/metadata/mirror.c
@@ -149,8 +149,8 @@ int insert_pvmove_mirrors(struct cmd_context *cmd,
 				       	seg->area[s].u.pv.pe,
 				       	PVMOVE, allocatable_pvs,
 				       	lv->alloc)) {
-					log_error("Allocation for temporary "
-					  	"pvmove LV failed");
+					log_error("Unable to allocate "
+						  "temporary LV for pvmove.");
 					return 0;
 				}
 				seg->area[s].type = AREA_LV;