diff --git a/mes/module/mes/posix.mes b/mes/module/mes/posix.mes
index c9c7165f..77785406 100644
--- a/mes/module/mes/posix.mes
+++ b/mes/module/mes/posix.mes
@@ -34,6 +34,9 @@
              (string-suffix? ext base)) (string-drop-right base (string-length ext))
              base)))
 
+(define (force-output . port)
+  *unspecified*)
+
 (define (search-path path file-name)
   (if (access? file-name R_OK) file-name
       (let loop ((path path))
diff --git a/src/mes.c b/src/mes.c
index fe31b968..8349cdb4 100644
--- a/src/mes.c
+++ b/src/mes.c
@@ -2128,7 +2128,6 @@ mes_builtins (SCM a) ///((internal))
   a = init_builtin (builtin_type, "open-output-file", -1, (function1_t)&open_output_file, a);
   a = init_builtin (builtin_type, "set-current-output-port", 1, (function1_t)&set_current_output_port, a);
   a = init_builtin (builtin_type, "set-current-error-port", 1, (function1_t)&set_current_error_port, a);
-  a = init_builtin (builtin_type, "force-output", -1, (function1_t)&force_output, a);
   a = init_builtin (builtin_type, "chmod", 2, (function1_t)&chmod_, a);
   a = init_builtin (builtin_type, "isatty?", 1, (function1_t)&isatty_p, a);
   a = init_builtin (builtin_type, "primitive-fork", 0, (function1_t)&primitive_fork, a);
diff --git a/src/posix.c b/src/posix.c
index d8316904..4935553d 100644
--- a/src/posix.c
+++ b/src/posix.c
@@ -245,12 +245,6 @@ set_current_error_port (SCM port)
   return current_error_port ();
 }
 
-SCM
-force_output (SCM p) ///((arity . n))
-{
-  return cell_unspecified;
-}
-
 SCM
 chmod_ (SCM file_name, SCM mode) ///((name . "chmod"))
 {