diff --git a/src/lib/formats/acorn_dsk.cpp b/src/lib/formats/acorn_dsk.cpp
index c597ee74995..64091ed887b 100644
--- a/src/lib/formats/acorn_dsk.cpp
+++ b/src/lib/formats/acorn_dsk.cpp
@@ -50,6 +50,18 @@ int acorn_ssd_format::find_size(io_generic *io, uint32_t form_factor)
 		if (memcmp(cat, "\x00\x28\x43\x29\x4a\x47\x48\x00", 4) == 0 && size == (uint64_t)compute_track_size(f) * f.track_count * f.head_count)
 			return i;
 
+		// test for Kenda SD - offset &0962 = 0 SD/1 DD, offset &0963 = disk size blocks / 4 (block size = 1K, ie. 0x400 bytes), reserved tracks = 3, ie. 0x1e00 bytes, soft stagger = 2 sectors, ie. 0x200 bytes
+		io_generic_read(io, cat, 0x0960, 8);
+		if (cat[2] == 0 && ((uint64_t)cat[3] * 4 * 0x400 + 0x2000) == size && size == (uint64_t)compute_track_size(f) * f.track_count * f.head_count)
+		{
+			// valid blocks for single sided
+			if (f.head_count == 1 && (cat[3] == 0x17 || cat[3] == 0x30))
+				return i;
+			// valid blocks for double sided
+			if (f.head_count == 2 && (cat[3] == 0x2f || cat[3] == 0x62))
+				return i;
+		}
+
 		// read sector count from side 0 catalogue
 		io_generic_read(io, cat, 0x100, 8);
 		sectors0 = ((cat[6] & 3) << 8) + cat[7];
@@ -59,7 +71,7 @@ int acorn_ssd_format::find_size(io_generic *io, uint32_t form_factor)
 			if (f.head_count == 2)
 			{
 				// read sector count from side 2 catalogue
-				io_generic_read(io, cat, compute_track_size(f) * f.track_count + 0x100, 8); // sequential
+				io_generic_read(io, cat, (uint64_t)compute_track_size(f) * f.track_count + 0x100, 8); // sequential
 				sectors2 = ((cat[6] & 3) << 8) + cat[7];
 
 				// exception case for Acorn CP/M System Disc 1
@@ -282,7 +294,7 @@ int opus_ddos_format::find_size(io_generic *io, uint32_t form_factor)
 			if (f.head_count == 2)
 			{
 				// read sector count from side 2 catalogue
-				io_generic_read(io, cat, compute_track_size(f) * f.track_count + 0x1000, 8); // sequential
+				io_generic_read(io, cat, (uint64_t)compute_track_size(f) * f.track_count + 0x1000, 8); // sequential
 				sectors2 = (cat[1] << 8) + cat[2];
 				LOG_FORMATS("ddos: sector count 2: %d %s\n", sectors2, sectors2 % 18 != 0 ? "invalid" : "");
 			}