diff --git a/srp/src/lib.rs b/srp/src/lib.rs
index bec6c11..d4a2dac 100644
--- a/srp/src/lib.rs
+++ b/srp/src/lib.rs
@@ -25,10 +25,9 @@
 //! |`a_pub = g^a`           | — `a_pub`, `I` —> | (lookup `s`, `v` for given `I`) |
 //! |`x = PH(P, s)`          | <— `b_pub`, `s` — | `b_pub = k*v + g^b`             |
 //! |`u = H(a_pub ‖ b_pub)`  |                   | `u = H(a_pub ‖ b_pub)`          |
-//! |`s = (b_pub - k*g^x)^(a+u*x)` |             | `S = (b_pub - k*g^x)^(a+u*x)`   |
-//! |`K = H(s)`              |                   | `K = H(s)`                      |
-//! |`M1 = H(A ‖ B ‖ K)`     |     — `M1` —>     | (verify `M1`)                   |
-//! |(verify `M2`)           |    <— `M2` —      | `M2 = H(A ‖ M1 ‖ K)`            |
+//! |`S = (b_pub - k*g^x)^(a+u*x)` |             | `S = (b_pub - k*g^x)^(a+u*x)`   |
+//! |`M1 = H(A ‖ B ‖ S)`     |     — `M1` —>     | (verify `M1`)                   |
+//! |(verify `M2`)           |    <— `M2` —      | `M2 = H(A ‖ M1 ‖ S)`            |
 //!
 //! Variables and notations have the following meaning:
 //!
diff --git a/srp/src/utils.rs b/srp/src/utils.rs
index 8232a73..e09fafe 100644
--- a/srp/src/utils.rs
+++ b/srp/src/utils.rs
@@ -45,7 +45,10 @@ pub fn compute_hash_n_xor_hash_g<D: Digest>(params: &SrpGroup) -> Vec<u8> {
         .collect()
 }
 
-// M1 = H(A, B, K) this doesn't follow the spec but apparently no one does for M1
+// M1 = H(A, B, S) follows SRP-6 required by a strict interpretation of RFC
+// 5054; this doesn't follow RFC 2945, where
+// M1 should equal =  H(H(N) XOR H(g) | H(U) | s | A | B | K) according to the spec
+// as RFC 5054 doesn't mandate its use.
 #[must_use]
 pub fn compute_m1<D: Digest>(a_pub: &[u8], b_pub: &[u8], key: &[u8]) -> Output<D> {
     let mut d = D::new();
@@ -82,7 +85,7 @@ pub fn compute_m1_rfc5054<D: Digest>(
     d.finalize()
 }
 
-// M2 = H(A, M1, K)
+// M2 = H(A, M1, S)
 #[must_use]
 pub fn compute_m2<D: Digest>(a_pub: &[u8], m1: &Output<D>, key: &[u8]) -> Output<D> {
     let mut d = D::new();