diff --git a/doc/api/fs.md b/doc/api/fs.md
index e95865db7fb200..01abd668c499b0 100644
--- a/doc/api/fs.md
+++ b/doc/api/fs.md
@@ -7973,6 +7973,9 @@ string.
 * `'r'`: Open file for reading.
   An exception occurs if the file does not exist.
 
+* `'rs'`: Open file for reading in synchronous mode.
+  An exception occurs if the file does not exist.
+
 * `'r+'`: Open file for reading and writing.
   An exception occurs if the file does not exist.