diff --git a/src/fields.rs b/src/fields.rs
index 9e01217..8e11528 100644
--- a/src/fields.rs
+++ b/src/fields.rs
@@ -7,6 +7,7 @@ mod fq;
 pub use fp::*;
 pub use fq::*;
 
+/// Converts 64-bit little-endian limbs to 32-bit little endian limbs.
 #[cfg(feature = "gpu")]
 fn u64_to_u32(limbs: &[u64]) -> alloc::vec::Vec<u32> {
     limbs