diff --git a/src/include/microhttpd.h b/src/include/microhttpd.h
index 933f146a..c850d849 100644
--- a/src/include/microhttpd.h
+++ b/src/include/microhttpd.h
@@ -2307,6 +2307,8 @@ union MHD_ConnectionInfo
 
   /**
    * Size of the client's HTTP header.
+   * It includes the request line, all request headers, the header section
+   * terminating empty line, with all CRLF (or LF) characters.
    */
   size_t header_size;
 
diff --git a/src/microhttpd/internal.h b/src/microhttpd/internal.h
index 27e9a50f..96178169 100644
--- a/src/microhttpd/internal.h
+++ b/src/microhttpd/internal.h
@@ -1097,6 +1097,8 @@ struct MHD_Request
   /**
    * Number of bytes we had in the HTTP header, set once we
    * pass #MHD_CONNECTION_HEADERS_RECEIVED.
+   * This includes the request line, all request headers, the header section
+   * terminating empty line, with all CRLF (or LF) characters.
    */
   size_t header_size;