diff --git a/doc/musig-spec.mediawiki b/doc/musig-spec.mediawiki
index 477f6e3cb..dff1ad4b7 100644
--- a/doc/musig-spec.mediawiki
+++ b/doc/musig-spec.mediawiki
@@ -157,7 +157,7 @@ The algorithm ''Sign(secnonce, sk, aggnonce, pk1..u, m)'' is defined
* Let ''d' = int(sk)''
* Fail if ''d' = 0'' or ''d' ≥ n''
* Let ''P = d'⋅G''
-* Let ''d = d' '' if ''has_even_y(P) `XOR` has_even_y(Q)'', otherwise let ''d = n - d' ''
+* Let ''d = n - d' '' if ''has_even_y(P) `XOR` has_even_y(Q)'', otherwise let ''d = d' ''
* Let ''e = int(hashBIP0340/challenge(bytes(R) || bytes(Q) || m)) mod n''
* Let ''mu = KeyAggCoeff(pk1..u, bytes(P))''
* Let ''s = (k1 + b⋅k2 + e⋅mu⋅d) mod n''