--- a/libinterp/corefcn/load-save.cc	Tue Feb 21 17:45:34 2023 -0500
+++ b/libinterp/corefcn/load-save.cc	Fri Feb 24 09:36:30 2023 -0500
@@ -1465,14 +1465,16 @@
     print_usage ();
   else
     {
-      // We make a new temporary filename, write to that instead of the
-      // file specified, then try renaming it at the end.
+      // For non-append mode, we make a new temporary filename, write to that
+      // instead of the file specified, then rename it at the end.
       // That way, if something goes wrong during the save like OOM,
       // we won't overwrite already-saved data in a file.
       // See bug #63803 for context.
+      // In append mode, this kind of guard is counterproductive so we write
+      // directly to the specified file.
 
       std::string desiredname = sys::file_ops::tilde_expand (argv[i]);
-      std::string fname = desiredname + ".saving_in_progress";
+      std::string fname = desiredname + (append ? "" : ".saving_in_progress");
 
       i++;
 
@@ -1553,13 +1555,16 @@
       // If we are all the way here without Octave crashing or running
       // out of memory etc, then we can say that writing to the
       // temporary file was successful. So now we try to rename it to
-      // the actual file that was specified.
-
-      std::string msg;
+      // the actual file that was specified, unless we were in append mode
+      // in which case we take no action.
 
-      if (octave::sys::rename (fname, desiredname, msg) < 0)
-        error ("save: unable to save to %s  %s",
-               desiredname.c_str (), msg.c_str ());
+      if (! append)
+        {
+          std::string msg;
+          if (octave::sys::rename (fname, desiredname, msg) < 0)
+            error ("save: unable to save to %s  %s",
+                   desiredname.c_str (), msg.c_str ());
+        }
     }
 
   return retval;