diff --git a/ff/src/lib.rs b/ff/src/lib.rs
index 482dc46..fd1a502 100644
--- a/ff/src/lib.rs
+++ b/ff/src/lib.rs
@@ -266,7 +266,7 @@ pub trait PrimeField: Field {
     }
 
     /// Convert this prime field element into a biginteger representation.
-    fn from_repr(Self::Repr) -> Result<Self, PrimeFieldDecodingError>;
+    fn from_repr(_: Self::Repr) -> Result<Self, PrimeFieldDecodingError>;
 
     /// Convert a biginteger representation into a prime field element, if
     /// the number is an element of the field.