diff --git a/TODO.md b/TODO.md
index cb075c5..92ca9ba 100644
--- a/TODO.md
+++ b/TODO.md
@@ -65,8 +65,6 @@ Follow-up:
 
 - Implement or deliberately reject the following endpoints after client evidence
   or direct protocol tests:
-  - `NCP 0x04 Lock File Set`: lock the current task's logged file set; related
-    release/clear set calls already use `share_handle_lock_sets()`.
   - `NCP 0x16/0x18 Restore Directory Handle`: verify the exact SDK
     request/reply layout, then implement the documented function 22 /
     subfunction 24 directory-handle semantics.
diff --git a/src/nwconn.c b/src/nwconn.c
index a54ce2f..61b0553 100644
--- a/src/nwconn.c
+++ b/src/nwconn.c
@@ -439,23 +439,34 @@ static int handle_ncp_serv(void)
       }
       break;
 
-#if 0
-      case 0x4 : { /* Lock File Set */
+      case 0x4 :   /* Lock File Set (old) */
+      case 0x6a : { /* Lock File Set       */
         /*
-         * TODO(ncp-compat): Implement NCP 0x04 Lock File Set.
+         * NCP 0x2222/04 Lock File Set (old) and NCP 0x2222/106 Lock
+         * File Set lock all files logged by the calling client's current
+         * task.
          *
-         * SDK context: locks every file previously entered in this task's
-         * file log table by Log File (0x03).  This is the set-oriented
-         * companion of Release File Set (0x06) and Clear File Set (0x08),
-         * which are already wired through share_handle_lock_sets().
+         * SDK request: 2-byte Lock Timeout, in units of 1/18 second;
+         * 0 means No Wait.
+         * SDK reply: no reply data.
+         * SDK completion: 0x00 success, 0xfe timeout, 0xff lock error.
          *
-         * Compatibility note: preserve NetWare's logged-set semantics; this
-         * is not the same as locking one pathname supplied by the request.
+         * The newer 0x6a call replaces the old 0x04 call but has the same
+         * request layout for the file set lock itself.  MARS-NWE records
+         * file-set members through Log File (0x03), then uses the shared
+         * set handler for Lock/Release/Clear File Set operations.
          */
-
+        struct INPUT {
+          uint8   header[7];       /* Requestheader */
+          uint8   timeout[2];      /* HI LO         */
+        } *input = (struct INPUT *) (ncprequest);
+        int result = share_handle_lock_sets(
+                                      1,   /* File Set */
+                                      0,   /* Lock logged entries */
+                                      GET_BE16(input->timeout));
+        if (result) completition = (uint8) -result;
       }
       break;
-#endif
       
       case 0x5 :    /* Release File  */
       case 0x7 : {  /* Clear File, removes file from logset */