diff --git a/doc/syscalls.md b/doc/syscalls.md
index aa91519..6661dd3 100644
--- a/doc/syscalls.md
+++ b/doc/syscalls.md
@@ -390,3 +390,23 @@ Argument Structure:
 This call attempts to move or rename the specified `source` file to `dest`. On success,
  `C` will contain  `STATUS_OK`. On error,  `C` will contain a negative value indicating the
 specific error.
+
+# `0x16`: Set File Attributes
+
+Arguments:
+ - `C`: `0x16`
+ - `X`: File handle
+ - `Y`: File attribute bitmask
+
+Return Values:
+ - `C`: Status code
+
+ This call alters the file attributes of the specified file. The `Y` register should
+ contain the result of a bitwise OR operation on any or all of the following values:
+
+ - `FILE_READ_ONLY`
+ - `FILE_HIDDEN`
+ - `FILE_SYSTEM`
+ - `FILE_ARCHIVE`
+
+ Passing `0x0000` in the `Y` register will clear all attributes.
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