diff --git a/docs/proposed/psa-driver-interface.md b/docs/proposed/psa-driver-interface.md
index 0027ec7..cd1b9fc 100644
--- a/docs/proposed/psa-driver-interface.md
+++ b/docs/proposed/psa-driver-interface.md
@@ -474,7 +474,8 @@
 * `PSA_JPAKE_X4S_STEP_ZK_PUBLIC`    Round 2: input Schnorr NIZKP public key for the X4S key
 * `PSA_JPAKE_X4S_STEP_ZK_PROOF`     Round 2: input Schnorr NIZKP proof for the X4S key
 
-The core checks that input_length is smaller than PSA_PAKE_INPUT_MAX_SIZE.
+The core checks that `input_length` is not greater than `PSA_PAKE_INPUT_SIZE(alg, prim, step)` and
+the driver can rely on that.
 
 ### PAKE driver get implicit key