diff --git a/src/util/os_misc.h b/src/util/os_misc.h
index 6a619c158b5..03cd59c3683 100644
--- a/src/util/os_misc.h
+++ b/src/util/os_misc.h
@@ -83,7 +83,8 @@ os_log_message(const char *message);
 
 
 /*
- * Get an option. Should return NULL if specified option is not set.
+ * Get an option(environment variable or os property) in a platform independent way.
+ * Should return NULL if specified option for @name is not set.
  * It has the same disadvantage as getenv, see
  * https://wiki.sei.cmu.edu/confluence/display/c/ENV34-C.+Do+not+store+pointers+returned+by+certain+functions
  */
@@ -101,7 +102,8 @@ char *
 os_get_option_dup(const char *name);
 
 /*
- * Get an option. Should return NULL if specified option is not set.
+ * Get an option(environment variable or os property) in a platform independent way.
+ * Should return NULL if specified option for @name is not set.
  * Same as `os_get_option()` but uses `secure_getenv()` instead of `getenv()`
  */
 const char *
@@ -118,12 +120,13 @@ char *
 os_get_option_secure_dup(const char *name);
 
 /*
- * Get an option. Should return NULL if specified option is not set.
+ * Get an option(environment variable or os property) in a platform independent way.
+ * Should return NULL if specified option for @name is not set.
  * It's will save the option into hash table for the first time, and
  * for latter calling, it's will return the value comes from hash table
  * directly, and the returned value will always be valid before program exit
- * The disadvantage is that setenv, unsetenv, putenv won't take effect
- * after this function is called
+ * The disadvantage is that os_set_option won't take effect after this
+ * function is called
  */
 const char *
 os_get_option_cached(const char *name);