diff --git a/scheme/base.sld b/scheme/base.sld
index bc0019ec..fca004da 100644
--- a/scheme/base.sld
+++ b/scheme/base.sld
@@ -138,6 +138,8 @@
     output-port?
     input-port-open?
     output-port-open?
+    get-output-string
+    open-output-string
     features
     Cyc-version
     any
@@ -193,9 +195,7 @@
 ;    ; need string ports
 ;    ; may be able to use POSIX string steams for this, see: open_memstream
 ;    ; however there may be portability issues with that. looks like BSD and windows don't have it
-;    get-output-string
 ;    open-input-string
-;    open-output-string
 ;
 ;    ;; no binary/text ports yet
 ;    binary-port?
@@ -1161,6 +1161,14 @@
         data, 
         k, 
        ((p->mode == 0 && p->fp != NULL) ? boolean_t : boolean_f)); ")
+  (define-c open-output-string
+    "(void *data, int argc, closure _, object k)"
+    " port_type p = Cyc_io_open_output_string(data);
+      return_closcall1(data, k, &p); ")
+  (define-c get-output-string
+    "(void *data, int argc, closure _, object k, object port)"
+    " Cyc_io_get_output_string(data, k, port);
+    ")
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; syntax-rules