diff --git a/misc/plugutils.c b/misc/plugutils.c
index 942a43611..d95a90a67 100644
--- a/misc/plugutils.c
+++ b/misc/plugutils.c
@@ -392,6 +392,18 @@ post_error (const char *oid, struct script_infos *desc, int port,
   proto_post_error (oid, desc, port, "tcp", action);
 }
 
+/**
+ * @brief Get the a plugins preference.
+ *
+ * Search in the preferences set by the client. If it is not
+ * present, search in redis cache for the default.
+ *
+ * @param[in] oid Script OID to get the preference from
+ * @param[in] name Name of the preference to get
+ * @param[in] pref_id Id of the preferences to get
+ *
+ * @return script preference on success, Null otherwise.
+ **/
 char *
 get_plugin_preference (const char *oid, const char *name, int pref_id)
 {
diff --git a/nasl/nasl_scanner_glue.c b/nasl/nasl_scanner_glue.c
index 3f49f1bd8..a14ab7675 100644
--- a/nasl/nasl_scanner_glue.c
+++ b/nasl/nasl_scanner_glue.c
@@ -492,6 +492,16 @@ script_add_preference (lex_ctxt *lexic)
   return FAKE_CELL;
 }
 
+/**
+ * @brief Get a preferences of the current script.
+ *
+ * Search the preference by preference name or by preferences id.
+ *
+ * @param[in] lexic     NASL lexer.
+ *
+ * @return lex cell containing the preferences value as a string.
+ *         Fake cell otherwise
+ */
 tree_cell *
 script_get_preference (lex_ctxt *lexic)
 {