diff --git a/implementations/rust/preserves/src/value/repr.rs b/implementations/rust/preserves/src/value/repr.rs
index 3b75ae9..cfd667f 100644
--- a/implementations/rust/preserves/src/value/repr.rs
+++ b/implementations/rust/preserves/src/value/repr.rs
@@ -230,6 +230,8 @@ impl<N: NestedValue<D>, D: Embeddable> From<u32> for Value<N, D> { fn from(v: u3
 impl<N: NestedValue<D>, D: Embeddable> From<i32> for Value<N, D> { fn from(v: i32) -> Self { Value::from(i128::from(v)) } }
 impl<N: NestedValue<D>, D: Embeddable> From<u64> for Value<N, D> { fn from(v: u64) -> Self { Value::from(i128::from(v)) } }
 impl<N: NestedValue<D>, D: Embeddable> From<i64> for Value<N, D> { fn from(v: i64) -> Self { Value::from(i128::from(v)) } }
+impl<N: NestedValue<D>, D: Embeddable> From<usize> for Value<N, D> { fn from(v: usize) -> Self { Value::from(v as u128) } }
+impl<N: NestedValue<D>, D: Embeddable> From<isize> for Value<N, D> { fn from(v: isize) -> Self { Value::from(v as i128) } }
 impl<N: NestedValue<D>, D: Embeddable> From<u128> for Value<N, D> { fn from(v: u128) -> Self { Value::SignedInteger(SignedInteger::from(v)) } }
 impl<N: NestedValue<D>, D: Embeddable> From<i128> for Value<N, D> { fn from(v: i128) -> Self { Value::SignedInteger(SignedInteger::from(v)) } }
 impl<N: NestedValue<D>, D: Embeddable> From<&BigInt> for Value<N, D> { fn from(v: &BigInt) -> Self { Value::SignedInteger(SignedInteger::from(Cow::Borrowed(v))) } }