diff --git a/src/client.js b/src/client.js
index c3d5e24e6..cf6579592 100644
--- a/src/client.js
+++ b/src/client.js
@@ -777,7 +777,8 @@ MatrixClient.prototype.getStoredDevice = async function(userId, deviceId) {
  * Mark the given device as verified
  *
  * @param {string} userId owner of the device
- * @param {string} deviceId unique identifier for the device
+ * @param {string} deviceId unique identifier for the device or user's
+ * cross-signing public key ID.
  *
  * @param {boolean=} verified whether to mark the device as verified. defaults
  *   to 'true'.
@@ -805,7 +806,8 @@ MatrixClient.prototype.setDeviceVerified = function(userId, deviceId, verified)
  * Mark the given device as blocked/unblocked
  *
  * @param {string} userId owner of the device
- * @param {string} deviceId unique identifier for the device
+ * @param {string} deviceId unique identifier for the device or user's
+ * cross-signing public key ID.
  *
  * @param {boolean=} blocked whether to mark the device as blocked. defaults
  *   to 'true'.
@@ -825,7 +827,8 @@ MatrixClient.prototype.setDeviceBlocked = function(userId, deviceId, blocked) {
  * Mark the given device as known/unknown
  *
  * @param {string} userId owner of the device
- * @param {string} deviceId unique identifier for the device
+ * @param {string} deviceId unique identifier for the device or user's
+ * cross-signing public key ID.
  *
  * @param {boolean=} known whether to mark the device as known. defaults
  *   to 'true'.
diff --git a/src/crypto/index.js b/src/crypto/index.js
index bc01fc2e7..899f06172 100644
--- a/src/crypto/index.js
+++ b/src/crypto/index.js
@@ -1418,7 +1418,8 @@ Crypto.prototype.saveDeviceList = function(delay) {
  * Update the blocked/verified state of the given device
  *
  * @param {string} userId owner of the device
- * @param {string} deviceId unique identifier for the device
+ * @param {string} deviceId unique identifier for the device or user's
+ * cross-signing public key ID.
  *
  * @param {?boolean} verified whether to mark the device as verified. Null to
  *     leave unchanged.