diff --git a/bip-taproot.mediawiki b/bip-taproot.mediawiki
index 7d646ea1..de266b9c 100644
--- a/bip-taproot.mediawiki
+++ b/bip-taproot.mediawiki
@@ -194,7 +194,7 @@ def taproot_tweak_pubkey(pubkey, h):
 
 def taproot_tweak_seckey(seckey0, h):
     P = point_mul(G, int_from_bytes(seckey0))
-    seckey = SECP256K1_ORDER - seckey0 if not has_square_y(R) else seckey
+    seckey = SECP256K1_ORDER - seckey0 if not has_square_y(P) else seckey
     t = int_from_bytes(tagged_hash("TapTweak", bytes_from_int(x(P)) + h))
     if t >= SECP256K1_ORDER:
         raise ValueError