diff --git a/core/src/header/extension/v1.rs b/core/src/header/extension/v1.rs
index a2dfc31e..390abed3 100644
--- a/core/src/header/extension/v1.rs
+++ b/core/src/header/extension/v1.rs
@@ -10,8 +10,8 @@ use crate::{v1::KateCommitment, DataLookup};
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "serde", serde(rename_all = "camelCase"))]
 pub struct HeaderExtension {
-	pub commitment: KateCommitment,
 	pub app_lookup: DataLookup,
+	pub commitment: KateCommitment,
 }
 
 impl HeaderExtension {
diff --git a/core/src/header/extension/v2.rs b/core/src/header/extension/v2.rs
index 0b0d0fc7..1f6d2813 100644
--- a/core/src/header/extension/v2.rs
+++ b/core/src/header/extension/v2.rs
@@ -10,13 +10,13 @@ use crate::{v2::KateCommitment, DataLookup};
 #[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
 #[cfg_attr(feature = "serde", serde(rename_all = "camelCase"))]
 pub struct HeaderExtension {
-	pub commitment: KateCommitment,
 	pub app_lookup: DataLookup,
+	pub commitment: KateCommitment,
 }
 
 impl HeaderExtension {
 	pub fn data_root(&self) -> H256 {
-		self.commitment.data_root.unwrap_or_default()
+		self.commitment.data_root
 	}
 
 	pub fn app_lookup(&self) -> &DataLookup {
diff --git a/core/src/header/mod.rs b/core/src/header/mod.rs
index 876d852c..bee251dd 100644
--- a/core/src/header/mod.rs
+++ b/core/src/header/mod.rs
@@ -366,13 +366,13 @@ mod tests {
 		};
 
 		let encoded = header.encode();
-		assert_eq!(encoded, hex!("92cdf578c47085a5992256f0dcf97d0b19f1f1c9de4d5fe30c3ace6191b6e5db08581348337b0f3e148620173daaa5f94d00d881705dcbf0aa83efdaba61d2ede1eb8649214997574e20c464388a172420d25403682bbbb80c496831c8cc1f8f0d040004350004103fbf3227926cfa3f4167771e5ad91cfa2c2d7090667ce01e911ca90b4f315b11810180e949ebdaf5c13e09649c587c6b1905fb770b4a6843abaac6b413e3a7405d9825ac764db2341db9b7965965073e975980e949ebdaf5c13e09649c587c6b1905fb770b4a6843abaac6b413e3a7405d9825ac764db2341db9b7965965073e97590000").to_vec());
+		assert_eq!(encoded, hex!("92cdf578c47085a5992256f0dcf97d0b19f1f1c9de4d5fe30c3ace6191b6e5db08581348337b0f3e148620173daaa5f94d00d881705dcbf0aa83efdaba61d2ede1eb8649214997574e20c464388a172420d25403682bbbb80c496831c8cc1f8f0d040004350000000410810180e949ebdaf5c13e09649c587c6b1905fb770b4a6843abaac6b413e3a7405d9825ac764db2341db9b7965965073e975980e949ebdaf5c13e09649c587c6b1905fb770b4a6843abaac6b413e3a7405d9825ac764db2341db9b7965965073e97593fbf3227926cfa3f4167771e5ad91cfa2c2d7090667ce01e911ca90b4f315b11").to_vec());
 	}
 
 	fn header_v1() -> THeader {
 		let commitment = v1::KateCommitment {
-				commitment: hex!("80e949ebdaf5c13e09649c587c6b1905fb770b4a6843abaac6b413e3a7405d9825ac764db2341db9b7965965073e975980e949ebdaf5c13e09649c587c6b1905fb770b4a6843abaac6b413e3a7405d9825ac764db2341db9b7965965073e9759").to_vec(),
 				data_root: hex!("3fbf3227926cfa3f4167771e5ad91cfa2c2d7090667ce01e911ca90b4f315b11").into(),
+				commitment: hex!("80e949ebdaf5c13e09649c587c6b1905fb770b4a6843abaac6b413e3a7405d9825ac764db2341db9b7965965073e975980e949ebdaf5c13e09649c587c6b1905fb770b4a6843abaac6b413e3a7405d9825ac764db2341db9b7965965073e9759").to_vec(),
 				..Default::default()
 			};
 		let extension = extension::v1::HeaderExtension {
@@ -405,13 +405,8 @@ mod tests {
 
 	/// It creates a corrupted V2 header and the associated error on decodification.
 	fn corrupted_header() -> (Vec<u8>, Error) {
-		let mut encoded = header_v2().encode();
-
-		// Change the discriminator
-		let discriminator = encoded.get_mut(98).expect("Discriminator at position 98");
-		assert_eq!(*discriminator, 1u8);
-		*discriminator = 0u8;
-		assert_eq!(*discriminator, 0u8);
+		let mut encoded = header_v1().encode();
+		encoded.remove(110);
 
 		let error = THeader::decode(&mut encoded.as_slice()).unwrap_err();
 
@@ -478,7 +473,7 @@ mod tests {
 		assert_eq!(
 			hash,
 			H256(hex!(
-				"21bbb83a624df177036ec0f5b03db7a5fcf47ce661138853743c72fef339b30b"
+				"2658abca4272bbd01abe73b29b0396dd03eb6af104a1d9b9e601d13d933a88b5"
 			))
 		);
 
@@ -508,7 +503,7 @@ mod tests {
 				ext.commitment.data_root = H256::repeat_byte(1u8);
 			},
 			extension::HeaderExtension::V2(ref mut ext) => {
-				ext.commitment.data_root = Some(H256::repeat_byte(2u8));
+				ext.commitment.data_root = H256::repeat_byte(2u8);
 			},
 		};
 
diff --git a/core/src/kate_commitment.rs b/core/src/kate_commitment.rs
index 7b72f65b..d688ae4d 100644
--- a/core/src/kate_commitment.rs
+++ b/core/src/kate_commitment.rs
@@ -25,10 +25,10 @@ pub mod v1 {
 		/// Cols
 		#[codec(compact)]
 		pub cols: u16,
-		/// The merkle root of the data submitted
-		pub data_root: H256,
 		/// Plonk commitment.
 		pub commitment: Vec<u8>,
+		/// The merkle root of the data submitted
+		pub data_root: H256,
 	}
 
 	#[cfg(feature = "serde")]
@@ -59,20 +59,19 @@ pub mod v2 {
 		/// Cols
 		#[codec(compact)]
 		pub cols: u16,
-		/// The merkle root of the data submitted
-		pub data_root: Option<H256>,
 		/// Plonk commitment.
 		pub commitment: Vec<u8>,
+		/// The merkle root of the data submitted
+		pub data_root: H256,
 	}
 
 	impl KateCommitment {
 		pub fn new(rows: u16, cols: u16, data_root: H256, commitment: Vec<u8>) -> Self {
-			let data_root = (!data_root.is_zero()).then_some(data_root);
 			Self {
 				rows,
 				cols,
-				data_root,
 				commitment,
+				data_root,
 			}
 		}
 	}
@@ -81,11 +80,7 @@ pub mod v2 {
 	impl fmt::Debug for KateCommitment {
 		fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 			let commitment = self.commitment.as_slice();
-			let data_root = self
-				.data_root
-				.as_ref()
-				.map(AsRef::as_ref)
-				.unwrap_or_default();
+			let data_root = self.data_root.as_ref();
 
 			f.debug_struct("KateCommitment(v2)")
 				.field("rows", &self.rows)
@@ -95,18 +90,4 @@ pub mod v2 {
 				.finish()
 		}
 	}
-
-	#[cfg(test)]
-	mod tests {
-		use super::*;
-		use test_case::test_case;
-
-		/// Double check that zero data root is compressed to `None`.
-		#[test_case( H256([0u8;32]) => None; "Zero data root")]
-		#[test_case( H256([1u8;32]) => Some(H256([1u8;32])); "NonZero data root")]
-		fn compression_on_new(data_root: H256) -> Option<H256> {
-			let kate = KateCommitment::new(1, 1, data_root, vec![]);
-			kate.data_root
-		}
-	}
 }