diff --git a/doc/ck_ht_entry_key_set b/doc/ck_ht_entry_key_set
index 155c4a6..f5ab2af 100644
--- a/doc/ck_ht_entry_key_set
+++ b/doc/ck_ht_entry_key_set
@@ -44,6 +44,9 @@ with a key pointed to by the
 .Fa key
 argument. The length of the key is specified by
 .Fa key_length.
+The maximum value of
+.Fa key_length
+is defined by the CK_HT_KEY_LENGTH macro.
 This function is typically used to initialize an
 entry for
 .Xr ck_ht_get_spmc 3
diff --git a/doc/ck_ht_entry_set b/doc/ck_ht_entry_set
index 91655a4..31da30f 100644
--- a/doc/ck_ht_entry_set
+++ b/doc/ck_ht_entry_set
@@ -46,6 +46,9 @@ argument and a value pointed to by the
 .Fa value
 argument. The length of the key is specified by
 .Fa key_length.
+The maximum value of
+.Fa key_length
+is defined by the CK_HT_KEY_LENGTH macro.
 This function is typically used to initialize an
 entry for
 .Xr ck_ht_set_spmc 3