diff --git a/libguile/strports.c b/libguile/strports.c
index e3ed62f85..5b5dbcb2e 100644
--- a/libguile/strports.c
+++ b/libguile/strports.c
@@ -363,7 +363,7 @@ SCM_DEFINE (scm_call_with_output_string, "call-with-output-string", 1, 0, 0,
                      FUNC_NAME);
   scm_call_1 (proc, p);
 
-  return scm_strport_to_string (p);
+  return scm_get_output_string (p);
 }
 #undef FUNC_NAME