diff --git a/src/constants.rs b/src/constants.rs
index 0a4db49..cb185e4 100644
--- a/src/constants.rs
+++ b/src/constants.rs
@@ -34,6 +34,14 @@ pub const MAX_SIGNATURE_SIZE: usize = 72;
 /// The maximum size of a compact signature
 pub const COMPACT_SIGNATURE_SIZE: usize = 64;
 
+/// The Prime for the secp256k1 field element.
+pub const FIELD_SIZE: [u8; 32] = [
+    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+    0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+    0xff, 0xff, 0xff, 0xfe, 0xff, 0xff, 0xfc, 0x2f
+];
+
 /// The order of the secp256k1 curve
 pub const CURVE_ORDER: [u8; 32] = [
     0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,