diff --git a/block/src/lib.rs b/block/src/lib.rs
index 288db3fbf..b6c083cef 100644
--- a/block/src/lib.rs
+++ b/block/src/lib.rs
@@ -70,7 +70,11 @@ use crate::vhdx::VhdxError;
 const SECTOR_SHIFT: u8 = 9;
 pub const SECTOR_SIZE: u64 = 0x01 << SECTOR_SHIFT;
 
-/// Field offsets within `struct virtio_blk_discard_write_zeroes`.
+/// Maximum number of segments per DISCARD or WRITE_ZEROES request.
+pub const MAX_DISCARD_WRITE_ZEROES_SEG: u32 = 1;
+
+/// Size and field offsets within `struct virtio_blk_discard_write_zeroes`.
+const DISCARD_WZ_SEG_SIZE: u32 = mem::size_of::<virtio_blk_discard_write_zeroes>() as u32;
 const DISCARD_WZ_SECTOR_OFFSET: u64 =
     mem::offset_of!(virtio_blk_discard_write_zeroes, sector) as u64;
 const DISCARD_WZ_NUM_SECTORS_OFFSET: u64 =
@@ -105,6 +109,8 @@ pub enum Error {
     RawFileError(#[source] std::io::Error),
     #[error("The requested operation does not support multiple descriptors")]
     TooManyDescriptors,
+    #[error("Request contains too many segments")]
+    TooManySegments,
     #[error("Failure in vhdx")]
     VhdxError(#[source] VhdxError),
 }
@@ -591,9 +597,12 @@ impl Request {
                     return Err(ExecuteError::BadRequest(Error::TooManyDescriptors));
                 };
 
-                if data_len < 16 {
+                if data_len < DISCARD_WZ_SEG_SIZE {
                     return Err(ExecuteError::BadRequest(Error::DescriptorLengthTooSmall));
                 }
+                if data_len > DISCARD_WZ_SEG_SIZE * MAX_DISCARD_WRITE_ZEROES_SEG {
+                    return Err(ExecuteError::BadRequest(Error::TooManySegments));
+                }
 
                 let mut discard_sector = [0u8; 8];
                 let mut discard_num_sectors = [0u8; 4];
@@ -630,9 +639,12 @@ impl Request {
                     return Err(ExecuteError::BadRequest(Error::TooManyDescriptors));
                 };
 
-                if data_len < 16 {
+                if data_len < DISCARD_WZ_SEG_SIZE {
                     return Err(ExecuteError::BadRequest(Error::DescriptorLengthTooSmall));
                 }
+                if data_len > DISCARD_WZ_SEG_SIZE * MAX_DISCARD_WRITE_ZEROES_SEG {
+                    return Err(ExecuteError::BadRequest(Error::TooManySegments));
+                }
 
                 let mut wz_sector = [0u8; 8];
                 let mut wz_num_sectors = [0u8; 4];
diff --git a/virtio-devices/src/block.rs b/virtio-devices/src/block.rs
index edd1327f4..97d7c58c1 100644
--- a/virtio-devices/src/block.rs
+++ b/virtio-devices/src/block.rs
@@ -23,7 +23,8 @@ use block::disk_file::DiskBackend;
 use block::error::BlockError;
 use block::fcntl::{LockError, LockGranularity, LockGranularityChoice, LockType, get_lock_state};
 use block::{
-    ExecuteAsync, ExecuteError, Request, RequestType, VirtioBlockConfig, build_serial, fcntl,
+    ExecuteAsync, ExecuteError, MAX_DISCARD_WRITE_ZEROES_SEG, Request, RequestType,
+    VirtioBlockConfig, build_serial, fcntl,
 };
 use event_monitor::event;
 use log::{debug, error, info, warn};
@@ -829,12 +830,12 @@ impl Block {
 
                 if avail_features & (1u64 << VIRTIO_BLK_F_WRITE_ZEROES) != 0 {
                     config.max_write_zeroes_sectors = u32::MAX;
-                    config.max_write_zeroes_seg = 1;
+                    config.max_write_zeroes_seg = MAX_DISCARD_WRITE_ZEROES_SEG;
                     config.write_zeroes_may_unmap = if discard_supported { 1 } else { 0 };
                 }
                 if avail_features & (1u64 << VIRTIO_BLK_F_DISCARD) != 0 {
                     config.max_discard_sectors = u32::MAX;
-                    config.max_discard_seg = 1;
+                    config.max_discard_seg = MAX_DISCARD_WRITE_ZEROES_SEG;
                     config.discard_sector_alignment = (logical_block_size / SECTOR_SIZE) as u32;
                 }