diff --git a/bip-0360/ref-impl/common/tests/data/p2mr_construction.json b/bip-0360/ref-impl/common/tests/data/p2mr_construction.json
index c6b9068384..fbee51b2ce 100644
--- a/bip-0360/ref-impl/common/tests/data/p2mr_construction.json
+++ b/bip-0360/ref-impl/common/tests/data/p2mr_construction.json
@@ -87,7 +87,7 @@
                 "bip350Address": "bc1zdskuzp4ts94h87ws0c7drmev3sf9dagewj8qsylyahfyqhf800hsam4d6e",
                 "scriptPathControlBlocks": [
                     "c1f224a923cd0021ab202ab139cc56802ddb92dcfc172b9212261a539df79a112a",
-                    "c18ad69ec7cf41c2a4001fd1f738bf1e505ce2277acdcaa63fe4765192497f47a7"
+                    "fb8ad69ec7cf41c2a4001fd1f738bf1e505ce2277acdcaa63fe4765192497f47a7"
                 ]
             }
         },
diff --git a/bip-0360/ref-impl/rust/tests/p2mr_construction.rs b/bip-0360/ref-impl/rust/tests/p2mr_construction.rs
index e9d93f7b91..d0afc21b6e 100644
--- a/bip-0360/ref-impl/rust/tests/p2mr_construction.rs
+++ b/bip-0360/ref-impl/rust/tests/p2mr_construction.rs
@@ -213,10 +213,15 @@ fn process_test_vector_p2mr(test_vector: &TestVector) -> anyhow::Result<()> {
         let leaf_id = script_to_id.get(script)
             .unwrap_or_else(|| panic!("leaf script not found in script_to_id map: {}", hex::encode(script.as_bytes())));
 
-        let derived_control_block: P2mrControlBlock = P2mrControlBlock{
-            merkle_branch: merkle_branch.clone(),
-        };
-        let derived_serialized_control_block = hex::encode(derived_control_block.serialize());
+        // BIP341 control byte layout: bits 7..1 = leaf_version, bit 0 = parity.
+        // `& 0xfe` (11111110) masks off bit 0, isolating the leaf version in the upper 7 bits.
+        // `| 0x01` sets bit 0 to 1: P2MR has no key-spend path, so parity is always 1.
+        let control_byte = (version.to_consensus() & 0xfe) | 0x01u8;
+        let mut cb_buf = vec![control_byte];
+        merkle_branch
+            .encode(&mut cb_buf)
+            .expect("encode should not fail");
+        let derived_serialized_control_block = hex::encode(&cb_buf);
 
         let expected_cb = &expected_control_blocks[*leaf_id as usize];
         assert_eq!(