diff --git a/Create.c b/Create.c
index ccda07b..1cadbcc 100644
--- a/Create.c
+++ b/Create.c
@@ -114,6 +114,7 @@ int Create(struct supertype *st, char *mddev,
 	struct mdinfo info, *infos;
 	int did_default = 0;
 	int do_default_layout = 0;
+	int do_default_chunk = 0;
 	unsigned long safe_mode_delay = 0;
 	char chosen_name[1024];
 	struct map_ent *map = NULL;
@@ -229,13 +230,9 @@ int Create(struct supertype *st, char *mddev,
 	case 10:
 	case 6:
 	case 0:
-		if (chunk == 0) {
-			if (st && st->ss->default_geometry)
-				st->ss->default_geometry(st, NULL, NULL, &chunk);
-			chunk = chunk ? : 512;
-			if (verbose > 0)
-				fprintf(stderr, Name ": chunk size defaults to %dK\n", chunk);
-		}
+		if (chunk == 0 || chunk == UnSet)
+			do_default_chunk = 1;
+			/* chunk will be set later */
 		break;
 	case LEVEL_LINEAR:
 		/* a chunksize of zero 0s perfectly valid (and preferred) since 2.6.16 */
@@ -264,7 +261,7 @@ int Create(struct supertype *st, char *mddev,
 		size &= ~(unsigned long long)(chunk - 1);
 	newsize = size * 2;
 	if (st && ! st->ss->validate_geometry(st, level, layout, raiddisks,
-					      chunk, size*2, NULL, &newsize, verbose>=0))
+					      &chunk, size*2, NULL, &newsize, verbose>=0))
 		return 1;
 	if (size == 0) {
 		size = newsize / 2;
@@ -308,10 +305,11 @@ int Create(struct supertype *st, char *mddev,
 					layout = default_layout(st, level, verbose);
 				if (st && !st->ss->validate_geometry
 					    	(st, level, layout, raiddisks,
-						 chunk, size*2, dname, &freesize,
+						 &chunk, size*2, dname, &freesize,
 						 verbose > 0)) {
 					free(st);
 					st = NULL;
+					chunk = do_default_chunk ? 0 : chunk;
 				}
 			}
 
@@ -329,7 +327,7 @@ int Create(struct supertype *st, char *mddev,
 				layout = default_layout(st, level, verbose);
 			if (!st->ss->validate_geometry(st, level, layout,
 						       raiddisks,
-						       chunk, size*2, dname,
+						       &chunk, size*2, dname,
 						       &freesize,
 						       verbose >= 0)) {
 
@@ -341,6 +339,11 @@ int Create(struct supertype *st, char *mddev,
 				continue;
 			}
 		}
+		if (verbose > 0 && do_default_chunk) {
+			do_default_chunk = 0;
+			fprintf(stderr, Name ": chunk size "
+				"defaults to %dK\n", chunk);
+		}
 
 		freesize /= 2; /* convert to K */
 		if (chunk) {
@@ -422,7 +425,7 @@ int Create(struct supertype *st, char *mddev,
 			/* size is meaningful */
 			if (!st->ss->validate_geometry(st, level, layout,
 						       raiddisks,
-						       chunk, minsize*2,
+						       &chunk, minsize*2,
 						       NULL, NULL, 0)) {
 				fprintf(stderr, Name ": devices too large for RAID level %d\n", level);
 				return 1;
diff --git a/mdadm.h b/mdadm.h
index 9f20ba1..a1be856 100644
--- a/mdadm.h
+++ b/mdadm.h
@@ -64,6 +64,7 @@ extern __off64_t lseek64 __P ((int __fd, __off64_t __offset, int __whence));
 #define BLKGETSIZE64 _IOR(0x12,114,size_t) /* return device size in bytes (u64 *arg) */
 #endif
 
+#define DEFAULT_CHUNK 512
 #define DEFAULT_BITMAP_CHUNK 4096
 #define DEFAULT_BITMAP_DELAY 5
 #define DEFAULT_MAX_WRITE_BEHIND 256
@@ -700,7 +701,7 @@ extern struct superswitch {
 	 */
 	int (*validate_geometry)(struct supertype *st, int level, int layout,
 				 int raiddisks,
-				 int chunk, unsigned long long size,
+				 int *chunk, unsigned long long size,
 				 char *subdev, unsigned long long *freesize,
 				 int verbose);
 
diff --git a/super-ddf.c b/super-ddf.c
index 287fa7f..c62d9ca 100644
--- a/super-ddf.c
+++ b/super-ddf.c
@@ -2545,13 +2545,13 @@ validate_geometry_ddf_container(struct supertype *st,
 
 static int validate_geometry_ddf_bvd(struct supertype *st,
 				     int level, int layout, int raiddisks,
-				     int chunk, unsigned long long size,
+				     int *chunk, unsigned long long size,
 				     char *dev, unsigned long long *freesize,
 				     int verbose);
 
 static int validate_geometry_ddf(struct supertype *st,
 				 int level, int layout, int raiddisks,
-				 int chunk, unsigned long long size,
+				 int *chunk, unsigned long long size,
 				 char *dev, unsigned long long *freesize,
 				 int verbose)
 {
@@ -2569,7 +2569,7 @@ static int validate_geometry_ddf(struct supertype *st,
 	if (level == LEVEL_CONTAINER) {
 		/* Must be a fresh device to add to a container */
 		return validate_geometry_ddf_container(st, level, layout,
-						       raiddisks, chunk,
+						       raiddisks, chunk?*chunk:0,
 						       size, dev, freesize,
 						       verbose);
 	}
@@ -2596,7 +2596,7 @@ static int validate_geometry_ddf(struct supertype *st,
 			 * chosen so that add_to_super/getinfo_super
 			 * can return them.
 			 */
-			return reserve_space(st, raiddisks, size, chunk, freesize);
+			return reserve_space(st, raiddisks, size, chunk?*chunk:0, freesize);
 		}
 		return 1;
 	}
@@ -2713,7 +2713,7 @@ validate_geometry_ddf_container(struct supertype *st,
 
 static int validate_geometry_ddf_bvd(struct supertype *st,
 				     int level, int layout, int raiddisks,
-				     int chunk, unsigned long long size,
+				     int *chunk, unsigned long long size,
 				     char *dev, unsigned long long *freesize,
 				     int verbose)
 {
@@ -2734,6 +2734,9 @@ static int validate_geometry_ddf_bvd(struct supertype *st,
 	if (!ddf)
 		return 0;
 
+	if (chunk && (*chunk == 0 || *chunk == UnSet))
+		*chunk = DEFAULT_CHUNK;
+
 	if (!dev) {
 		/* General test:  make sure there is space for
 		 * 'raiddisks' device extents of size 'size'.
diff --git a/super-gpt.c b/super-gpt.c
index f60a671..6f852aa 100644
--- a/super-gpt.c
+++ b/super-gpt.c
@@ -193,7 +193,7 @@ static struct supertype *match_metadata_desc(char *arg)
 #ifndef MDASSEMBLE
 static int validate_geometry(struct supertype *st, int level,
 			     int layout, int raiddisks,
-			     int chunk, unsigned long long size,
+			     int *chunk, unsigned long long size,
 			     char *subdev, unsigned long long *freesize,
 			     int verbose)
 {
diff --git a/super-intel.c b/super-intel.c
index f3e248e..e8d2c6b 100644
--- a/super-intel.c
+++ b/super-intel.c
@@ -4165,17 +4165,21 @@ static int is_raid_level_supported(const struct imsm_orom *orom, int level, int
 #define pr_vrb(fmt, arg...) (void) (verbose && fprintf(stderr, Name fmt, ##arg))
 static int
 validate_geometry_imsm_orom(struct intel_super *super, int level, int layout,
-			    int raiddisks, int chunk, int verbose)
+			    int raiddisks, int *chunk, int verbose)
 {
 	if (!is_raid_level_supported(super->orom, level, raiddisks)) {
 		pr_vrb(": platform does not support raid%d with %d disk%s\n",
 			level, raiddisks, raiddisks > 1 ? "s" : "");
 		return 0;
 	}
-	if (super->orom && level != 1 &&
-	    !imsm_orom_has_chunk(super->orom, chunk)) {
-		pr_vrb(": platform does not support a chunk size of: %d\n", chunk);
-		return 0;
+	if (super->orom && level != 1) {
+		if (chunk && (*chunk == 0 || *chunk == UnSet))
+			*chunk = imsm_orom_default_chunk(super->orom);
+		else if (chunk && !imsm_orom_has_chunk(super->orom, *chunk)) {
+			pr_vrb(": platform does not support a chunk size of: "
+			       "%d\n", *chunk);
+			return 0;
+		}
 	}
 	if (layout != imsm_level_to_layout(level)) {
 		if (level == 5)
@@ -4195,7 +4199,7 @@ validate_geometry_imsm_orom(struct intel_super *super, int level, int layout,
  * FIX ME add ahci details
  */
 static int validate_geometry_imsm_volume(struct supertype *st, int level,
-					 int layout, int raiddisks, int chunk,
+					 int layout, int raiddisks, int *chunk,
 					 unsigned long long size, char *dev,
 					 unsigned long long *freesize,
 					 int verbose)
@@ -4414,7 +4418,7 @@ static int reserve_space(struct supertype *st, int raiddisks,
 }
 
 static int validate_geometry_imsm(struct supertype *st, int level, int layout,
-				  int raiddisks, int chunk, unsigned long long size,
+				  int raiddisks, int *chunk, unsigned long long size,
 				  char *dev, unsigned long long *freesize,
 				  int verbose)
 {
@@ -4428,7 +4432,8 @@ static int validate_geometry_imsm(struct supertype *st, int level, int layout,
 	if (level == LEVEL_CONTAINER) {
 		/* Must be a fresh device to add to a container */
 		return validate_geometry_imsm_container(st, level, layout,
-							raiddisks, chunk, size,
+							raiddisks,
+							chunk?*chunk:0, size,
 							dev, freesize,
 							verbose);
 	}
@@ -4447,7 +4452,8 @@ static int validate_geometry_imsm(struct supertype *st, int level, int layout,
 							 raiddisks, chunk,
 							 verbose))
 				return 0;
-			return reserve_space(st, raiddisks, size, chunk, freesize);
+			return reserve_space(st, raiddisks, size,
+					     chunk?*chunk:0, freesize);
 		}
 		return 1;
 	}
@@ -6925,6 +6931,7 @@ enum imsm_reshape_type imsm_analyze_change(struct supertype *st,
 	struct mdinfo info;
 	int change = -1;
 	int check_devs = 0;
+	int chunk;
 
 	getinfo_super_imsm_volume(st, &info, NULL);
 
@@ -6999,11 +7006,12 @@ enum imsm_reshape_type imsm_analyze_change(struct supertype *st,
 	else
 		geo->chunksize = info.array.chunk_size;
 
+	chunk = geo->chunksize / 1024;
 	if (!validate_geometry_imsm(st,
 				    geo->level,
 				    geo->layout,
 				    geo->raid_disks,
-				    (geo->chunksize / 1024),
+				    &chunk,
 				    geo->size,
 				    0, 0, 1))
 		change = -1;
diff --git a/super-mbr.c b/super-mbr.c
index 7d770aa..5eefdf6 100644
--- a/super-mbr.c
+++ b/super-mbr.c
@@ -187,7 +187,7 @@ static struct supertype *match_metadata_desc(char *arg)
 #ifndef MDASSEMBLE
 static int validate_geometry(struct supertype *st, int level,
 			     int layout, int raiddisks,
-			     int chunk, unsigned long long size,
+			     int *chunk, unsigned long long size,
 			     char *subdev, unsigned long long *freesize,
 			     int verbose)
 {
diff --git a/super0.c b/super0.c
index 0b95dac..832072d 100644
--- a/super0.c
+++ b/super0.c
@@ -1090,7 +1090,7 @@ static void free_super0(struct supertype *st)
 #ifndef MDASSEMBLE
 static int validate_geometry0(struct supertype *st, int level,
 			      int layout, int raiddisks,
-			      int chunk, unsigned long long size,
+			      int *chunk, unsigned long long size,
 			      char *subdev, unsigned long long *freesize,
 			      int verbose)
 {
@@ -1116,6 +1116,9 @@ static int validate_geometry0(struct supertype *st, int level,
 	if (!subdev)
 		return 1;
 
+	if (chunk && (*chunk == 0 || *chunk == UnSet))
+		*chunk = DEFAULT_CHUNK;
+
 	fd = open(subdev, O_RDONLY|O_EXCL, 0);
 	if (fd < 0) {
 		if (verbose)
diff --git a/super1.c b/super1.c
index 50a5f48..be05916 100644
--- a/super1.c
+++ b/super1.c
@@ -1654,7 +1654,7 @@ static void free_super1(struct supertype *st)
 #ifndef MDASSEMBLE
 static int validate_geometry1(struct supertype *st, int level,
 			      int layout, int raiddisks,
-			      int chunk, unsigned long long size,
+			      int *chunk, unsigned long long size,
 			      char *subdev, unsigned long long *freesize,
 			      int verbose)
 {
@@ -1669,6 +1669,9 @@ static int validate_geometry1(struct supertype *st, int level,
 	if (!subdev)
 		return 1;
 
+	if (chunk && (*chunk == 0 || *chunk == UnSet))
+		*chunk = DEFAULT_CHUNK;
+
 	fd = open(subdev, O_RDONLY|O_EXCL, 0);
 	if (fd < 0) {
 		if (verbose)