diff --git a/libc/stdio/vasprintf.c b/libc/stdio/vasprintf.c
new file mode 100644
index 0000000..c3280c9
--- /dev/null
+++ b/libc/stdio/vasprintf.c
@@ -0,0 +1,58 @@
+/*	$OpenBSD: vasprintf.c,v 1.13 2006/01/06 18:53:04 millert Exp $	*/
+
+/*
+ * Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include "local.h"
+
+int
+vasprintf(char **str, const char *fmt, __va_list ap)
+{
+	int ret;
+	FILE f;
+	struct __sfileext fext;
+	unsigned char *_base;
+
+	_FILEEXT_SETUP(&f, &fext);
+	f._file = -1;
+	f._flags = __SWR | __SSTR | __SALC;
+	f._bf._base = f._p = (unsigned char *)malloc(128);
+	if (f._bf._base == NULL)
+		goto err;
+	f._bf._size = f._w = 127;		/* Leave room for the NUL */
+	ret = vfprintf(&f, fmt, ap);
+	if (ret == -1)
+		goto err;
+	*f._p = '\0';
+	_base = realloc(f._bf._base, ret + 1);
+	if (_base == NULL)
+		goto err;
+	*str = (char *)_base;
+	return (ret);
+
+err:
+	if (f._bf._base) {
+		free(f._bf._base);
+		f._bf._base = NULL;
+	}
+	*str = NULL;
+	errno = ENOMEM;
+	return (-1);
+}