diff --git a/src/fr_sp1.rs b/src/fr_sp1.rs
index f38a2e0..3f500f2 100644
--- a/src/fr_sp1.rs
+++ b/src/fr_sp1.rs
@@ -130,7 +130,7 @@ impl Fr {
         CtOption::new(Fr(tmp), Choice::from(is_some))
     }
 
-    pub fn from_raw(limbs: [u64; 4]) -> Fr {
+    pub const fn from_raw(limbs: [u64; 4]) -> Fr {
         // FIXME: handle limbs that are larger than modulus.
         let mut tmp = [0, 0, 0, 0, 0, 0, 0, 0];