diff --git a/NEWS b/NEWS
index 484e31ea4..39b4fc05d 100644
--- a/NEWS
+++ b/NEWS
@@ -401,6 +401,13 @@ Set/remove an advisory shared or exclusive lock on `file'.
 Set or get the hostname of the machine the current process is running
 on.
 
+** New function: mkstemp! tmpl
+mkstemp creates a new unique file in the file system and returns a
+new buffered port open for reading and writing to the file.  TMPL
+is a string specifying where the file should be created: it must
+end with `XXXXXX' and will be changed in place to return the name
+of the temporary file.
+
 ** New function: open-input-string string
 
 Return an input string port which delivers the characters from
diff --git a/libguile/ChangeLog b/libguile/ChangeLog
index 49708a9d9..847dbc5b4 100644
--- a/libguile/ChangeLog
+++ b/libguile/ChangeLog
@@ -1,5 +1,10 @@
 2001-03-18  Gary Houston  <ghouston@arglist.com>
 
+	* posix.c (scm_tmpnam): check that return value from tmpnam is not
+	NULL.  rewrote the docstring.
+	(scm_mkstemp): new procedure implementing "mkstemp!".
+	* posix.h: declare scm_mkstemp.
+
 	* net_db.c: declare h_errno if configure didn't define HAVE_H_ERRNO.
 	normally it would be found in netdb.h.
 
diff --git a/libguile/posix.c b/libguile/posix.c
index efc3f4635..d1d54b42b 100644
--- a/libguile/posix.c
+++ b/libguile/posix.c
@@ -1028,19 +1028,48 @@ SCM_DEFINE (scm_environ, "environ", 0, 1, 0,
 
 SCM_DEFINE (scm_tmpnam, "tmpnam", 0, 0, 0,
             (),
-	    "Create a new file in the file system with a unique name.  The return\n"
-	    "value is the name of the new file.  This function is implemented with\n"
-	    "the @code{tmpnam} function in the system libraries.")
+	    "tmpnam returns a name in the file system that does not match\n"
+	    "any existing file.  However there is no guarantee that\n"
+	    "another process will not create the file after tmpnam\n"
+	    "is called.  Care should be taken if opening the file,\n"
+	    "e.g., use the O_EXCL open flag or use @code{mkstemp!} instead.")
 #define FUNC_NAME s_scm_tmpnam
 {
   char name[L_tmpnam];
-  SCM_SYSCALL (tmpnam (name););
+  char *rv;
+
+  SCM_SYSCALL (rv = tmpnam (name));
+  if (rv == NULL)
+    /* not SCM_SYSERROR since errno probably not set.  */
+    SCM_MISC_ERROR ("tmpnam failed", SCM_EOL);
   return scm_makfrom0str (name);
 }
 #undef FUNC_NAME
 
 #endif
 
+SCM_DEFINE (scm_mkstemp, "mkstemp!", 1, 0, 0,
+	    (SCM tmpl),
+	    "mkstemp creates a new unique file in the file system and\n"
+	    "returns a new buffered port open for reading and writing to\n"
+	    "the file.  @var{tmpl} is a string specifying where the\n"
+	    "file should be created: it must end with @code{XXXXXX}\n"
+	    "and will be changed in place to return the name of the\n"
+	    "temporary file.\n")
+#define FUNC_NAME s_scm_mkstemp
+{
+  char *c_tmpl;
+  int rv;
+  
+  SCM_STRING_COERCE_0TERMINATION_X (tmpl);
+  SCM_VALIDATE_STRING_COPY (1, tmpl, c_tmpl);
+  SCM_SYSCALL (rv = mkstemp (c_tmpl));
+  if (rv == -1)
+    SCM_SYSERROR;
+  return scm_fdes_to_port (rv, "w+", tmpl);
+}
+#undef FUNC_NAME
+
 SCM_DEFINE (scm_utime, "utime", 1, 2, 0,
             (SCM pathname, SCM actime, SCM modtime),
 	    "@code{utime} sets the access and modification times for\n"
diff --git a/libguile/posix.h b/libguile/posix.h
index 2b96f94e8..7d6d65743 100644
--- a/libguile/posix.h
+++ b/libguile/posix.h
@@ -2,7 +2,7 @@
 
 #ifndef POSIXH
 #define POSIXH
-/*	Copyright (C) 1995, 1996, 1997, 1998, 2000 Free Software Foundation, Inc.
+/*	Copyright (C) 1995, 1996, 1997, 1998, 2000, 2001 Free Software Foundation, Inc.
  * 
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -85,6 +85,7 @@ extern SCM scm_fork (void);
 extern SCM scm_uname (void);
 extern SCM scm_environ (SCM env);
 extern SCM scm_tmpnam (void);
+extern SCM scm_mkstemp (SCM tmpl);
 extern SCM scm_open_pipe (SCM pipestr, SCM modes);
 extern SCM scm_close_pipe (SCM port);
 extern SCM scm_utime (SCM pathname, SCM actime, SCM modtime);