diff --git a/rust/src/tx_builder.rs b/rust/src/tx_builder.rs
index 0a3f9efc..fd40cd2e 100644
--- a/rust/src/tx_builder.rs
+++ b/rust/src/tx_builder.rs
@@ -38,11 +38,12 @@ fn witness_keys_for_cert(cert_enum: &Certificate, keys: &mut BTreeSet<Ed25519Key
 }
 
 fn fake_private_key() -> Bip32PrivateKey {
-    Bip32PrivateKey::from_bip39_entropy(
-        // art forum devote street sure rather head chuckle guard poverty release quote oak craft enemy
-        &[0x0c, 0xcb, 0x74, 0xf3, 0x6b, 0x7d, 0xa1, 0x64, 0x9a, 0x81, 0x44, 0x67, 0x55, 0x22, 0xd4, 0xd8, 0x09, 0x7c, 0x64, 0x12],
-        &[]
-    )
+    Bip32PrivateKey::from_bytes(
+        &[0xb8, 0xf2, 0xbe, 0xce, 0x9b, 0xdf, 0xe2, 0xb0, 0x28, 0x2f, 0x5b, 0xad, 0x70, 0x55, 0x62, 0xac, 0x99, 0x6e, 0xfb, 0x6a, 0xf9, 0x6b, 0x64, 0x8f,
+            0x44, 0x45, 0xec, 0x44, 0xf4, 0x7a, 0xd9, 0x5c, 0x10, 0xe3, 0xd7, 0x2f, 0x26, 0xed, 0x07, 0x54, 0x22, 0xa3, 0x6e, 0xd8, 0x58, 0x5c, 0x74, 0x5a,
+            0x0e, 0x11, 0x50, 0xbc, 0xce, 0xba, 0x23, 0x57, 0xd0, 0x58, 0x63, 0x69, 0x91, 0xf3, 0x8a, 0x37, 0x91, 0xe2, 0x48, 0xde, 0x50, 0x9c, 0x07, 0x0d,
+            0x81, 0x2a, 0xb2, 0xfd, 0xa5, 0x78, 0x60, 0xac, 0x87, 0x6b, 0xc4, 0x89, 0x19, 0x2c, 0x1e, 0xf4, 0xce, 0x25, 0x3c, 0x19, 0x7e, 0xe2, 0x19, 0xa4]
+    ).unwrap()
 }
 
 // tx_body must be the result of building from tx_builder