diff --git a/src/curr/hash.rs b/src/curr/hash.rs
index 1bc3b840..7605d4ae 100644
--- a/src/curr/hash.rs
+++ b/src/curr/hash.rs
@@ -4,6 +4,6 @@ mod bytes;
 #[cfg(feature = "hex")]
 impl super::Hash {
     pub fn from_hex(s: &str) -> Result<Self, hex::FromHexError> {
-        Ok(super::Hash(create::hex::padded_hex_from_str(s)?))
+        Ok(super::Hash(crate::hex::padded_hex_from_str(s)?))
     }
 }
diff --git a/src/curr/hash/bytes.rs b/src/curr/hash/bytes.rs
index a1531d09..b007fb3a 100644
--- a/src/curr/hash/bytes.rs
+++ b/src/curr/hash/bytes.rs
@@ -15,6 +15,7 @@ impl TryFrom<HashIdPreimage> for Hash {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl TryFrom<HashIdPreimage> for stellar_strkey::Contract {
     type Error = super::super::Error;
     fn try_from(value: HashIdPreimage) -> Result<Self, Self::Error> {
diff --git a/src/curr/num_conversions.rs b/src/curr/num_conversions.rs
index 153e6673..743dce8e 100644
--- a/src/curr/num_conversions.rs
+++ b/src/curr/num_conversions.rs
@@ -21,6 +21,14 @@ impl From<(u128, u128)> for UInt256Parts {
     }
 }
 
+impl From<UInt256Parts> for (u128, u128) {
+    fn from(parts: UInt256Parts) -> Self {
+        let hi = (u128::from(parts.hi_hi) << 64) | u128::from(parts.hi_lo);
+        let lo = (u128::from(parts.lo_hi) << 64) | u128::from(parts.lo_lo);
+        (hi, lo)
+    }
+}
+
 impl From<(i128, i128)> for Int256Parts {
     fn from((hi, lo): (i128, i128)) -> Self {
         let Int128Parts {
@@ -40,6 +48,14 @@ impl From<(i128, i128)> for Int256Parts {
     }
 }
 
+impl From<Int256Parts> for (i128, i128) {
+    fn from(parts: Int256Parts) -> Self {
+        let hi = (i128::from(parts.hi_hi) << 64) | i128::from(parts.hi_lo);
+        let lo = (i128::from(parts.lo_hi) << 64) | i128::from(parts.lo_lo);
+        (hi, lo)
+    }
+}
+
 impl From<u128> for UInt128Parts {
     fn from(val: u128) -> Self {
         let hi = (val >> 64) as u64;
@@ -99,14 +115,3 @@ impl FromStr for Int128Parts {
         Ok(i128::from_str(s).map_err(|_| Self::Err::Invalid)?.into())
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::*;
-    #[test]
-    fn round_trip_u128() {
-        let u128_val: u128 = 0x1234567890abcdef1234567890abcdefu128;
-        let xdr_val: UInt128Parts = u128_val.into();
-        assert_eq!(xdr_val.into(), u128_val);
-    }
-}
diff --git a/src/next/hash.rs b/src/next/hash.rs
index 1bc3b840..7605d4ae 100644
--- a/src/next/hash.rs
+++ b/src/next/hash.rs
@@ -4,6 +4,6 @@ mod bytes;
 #[cfg(feature = "hex")]
 impl super::Hash {
     pub fn from_hex(s: &str) -> Result<Self, hex::FromHexError> {
-        Ok(super::Hash(create::hex::padded_hex_from_str(s)?))
+        Ok(super::Hash(crate::hex::padded_hex_from_str(s)?))
     }
 }
diff --git a/src/next/hash/bytes.rs b/src/next/hash/bytes.rs
index a1531d09..b007fb3a 100644
--- a/src/next/hash/bytes.rs
+++ b/src/next/hash/bytes.rs
@@ -15,6 +15,7 @@ impl TryFrom<HashIdPreimage> for Hash {
     }
 }
 
+#[cfg(feature = "alloc")]
 impl TryFrom<HashIdPreimage> for stellar_strkey::Contract {
     type Error = super::super::Error;
     fn try_from(value: HashIdPreimage) -> Result<Self, Self::Error> {
diff --git a/src/next/num_conversions.rs b/src/next/num_conversions.rs
index 153e6673..743dce8e 100644
--- a/src/next/num_conversions.rs
+++ b/src/next/num_conversions.rs
@@ -21,6 +21,14 @@ impl From<(u128, u128)> for UInt256Parts {
     }
 }
 
+impl From<UInt256Parts> for (u128, u128) {
+    fn from(parts: UInt256Parts) -> Self {
+        let hi = (u128::from(parts.hi_hi) << 64) | u128::from(parts.hi_lo);
+        let lo = (u128::from(parts.lo_hi) << 64) | u128::from(parts.lo_lo);
+        (hi, lo)
+    }
+}
+
 impl From<(i128, i128)> for Int256Parts {
     fn from((hi, lo): (i128, i128)) -> Self {
         let Int128Parts {
@@ -40,6 +48,14 @@ impl From<(i128, i128)> for Int256Parts {
     }
 }
 
+impl From<Int256Parts> for (i128, i128) {
+    fn from(parts: Int256Parts) -> Self {
+        let hi = (i128::from(parts.hi_hi) << 64) | i128::from(parts.hi_lo);
+        let lo = (i128::from(parts.lo_hi) << 64) | i128::from(parts.lo_lo);
+        (hi, lo)
+    }
+}
+
 impl From<u128> for UInt128Parts {
     fn from(val: u128) -> Self {
         let hi = (val >> 64) as u64;
@@ -99,14 +115,3 @@ impl FromStr for Int128Parts {
         Ok(i128::from_str(s).map_err(|_| Self::Err::Invalid)?.into())
     }
 }
-
-#[cfg(test)]
-mod test {
-    use super::*;
-    #[test]
-    fn round_trip_u128() {
-        let u128_val: u128 = 0x1234567890abcdef1234567890abcdefu128;
-        let xdr_val: UInt128Parts = u128_val.into();
-        assert_eq!(xdr_val.into(), u128_val);
-    }
-}
diff --git a/tests/num_conversions.rs b/tests/num_conversions.rs
index 0b16c309..0c8291f0 100644
--- a/tests/num_conversions.rs
+++ b/tests/num_conversions.rs
@@ -6,10 +6,10 @@
 
 #[cfg(feature = "curr")]
 use stellar_xdr::curr as stellar_xdr;
-// #[cfg(feature = "next")]
-// use stellar_xdr::next as stellar_xdr;
+#[cfg(feature = "next")]
+use stellar_xdr::next as stellar_xdr;
 
-use stellar_xdr::{Int128Parts, UInt128Parts};
+use stellar_xdr::{Int128Parts, UInt128Parts, UInt256Parts};
 
 #[test]
 fn round_trip_u128() {
@@ -29,8 +29,16 @@ fn round_trip_i128() {
 
 #[test]
 fn round_trip_u256() {
-    let u256_val = 0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdefu128;
-    let xdr_val: UInt128Parts = u256_val.into();
-    let u256_val2: u128 = xdr_val.into();
-    assert_eq!(u256_val, u256_val2);
+    let (hi, lo) = (0x1234567890abcdefu128, 0x1234567890abcdefu128);
+    let xdr_val: UInt256Parts = (hi, lo).into();
+    let (hi2, lo2): (u128, u128) = xdr_val.into();
+    assert_eq!((hi, lo), (hi2, lo2));
+}
+
+#[test]
+fn round_trip_i256() {
+    let (hi, lo) = (0x1234567890abcdefi128, 0x1234567890abcdefi128);
+    let xdr_val: Int256Parts = (hi, lo).into();
+    let (hi2, lo2): (i128, i128) = xdr_val.into();
+    assert_eq!((hi, lo), (hi2, lo2));
 }