diff --git a/libc/string/strerror_r.c b/libc/string/strerror_r.c
new file mode 100644
index 0000000..f43d417
--- /dev/null
+++ b/libc/string/strerror_r.c
@@ -0,0 +1,163 @@
+/* $OpenBSD: strerror_r.c,v 1.6 2005/08/08 08:05:37 espie Exp $ */
+/* Public Domain <marc@snafu.org> */
+
+#define sys_siglist	_sys_siglist
+
+#include <errno.h>
+#include <limits.h>
+#include <signal.h>
+#include <string.h>
+
+typedef struct {
+  int           code;
+  const char*   msg;
+} CodeString;
+
+static const char*
+__code_string_lookup( const CodeString*  strings,
+                      int                code )
+{
+    int  nn = 0;
+
+    for (;;)
+    {
+        if (strings[nn].code == 0)
+            break;
+
+        if (strings[nn].code == code)
+            return strings[nn].msg;
+
+        nn++;
+    }
+    return NULL;
+}
+
+
+static const CodeString  _sys_error_strings[] =
+{
+#define  __BIONIC_ERRDEF(x,y,z)  { y, z },
+#include <sys/_errdefs.h>
+    { 0, NULL }
+};
+
+static size_t
+__digits10(unsigned int num)
+{
+	size_t i = 0;
+
+	do {
+		num /= 10;
+		i++;
+	} while (num != 0);
+
+	return i;
+}
+
+static int
+__itoa(int num, int sign, char *buffer, size_t start, size_t end)
+{
+	size_t pos;
+	unsigned int a;
+	int neg;
+
+	if (sign && num < 0) {
+		a = -num;
+		neg = 1;
+	}
+	else {
+		a = num;
+		neg = 0;
+	}
+
+	pos = start + __digits10(a);
+	if (neg)
+	    pos++;
+
+	if (pos < end)
+		buffer[pos] = '\0';
+	else
+		return ERANGE;
+	pos--;
+	do {
+		buffer[pos] = (a % 10) + '0';
+		pos--;
+		a /= 10;
+	} while (a != 0);
+	if (neg)
+		buffer[pos] = '-';
+	return 0;
+}
+
+
+int
+strerror_r(int errnum, char *strerrbuf, size_t buflen)
+{
+    int          save_errno;
+    int          len, ret = 0;
+    const char*  msg;
+
+    save_errno = errno;
+    msg        = __code_string_lookup( _sys_error_strings, errnum );
+    if (msg != NULL) {
+        len = strlcpy(strerrbuf, msg, buflen);
+        if ((size_t)len >= buflen)
+            ret = ERANGE;
+    } else {
+        len = strlcpy(strerrbuf, "Unknown error: ", buflen);
+        if ((size_t)len >= buflen)
+            ret = ERANGE;
+        else {
+            int  ret = __itoa(errnum, 1, strerrbuf, len, buflen);
+
+            if (ret == 0)
+                ret = EINVAL;
+        }
+    }
+    return ret;
+}
+
+#if 0
+static const CodeString  _sys_signal_strings[] =
+{
+#define  SIGDEF(x,y,z)  { y, z },
+#include <sys/_sigdefs.h>
+};
+
+
+static int
+__num2string(int num, int sign, int setid, char *buf, size_t buflen,
+    char * list[], size_t max, const char *def)
+{
+	int ret = 0;
+	size_t len;
+
+	if (0 <= num && num < max) {
+		len = strlcpy(buf, def, buflen);
+		if (len >= buflen)
+			ret = ERANGE;
+	} else {
+		len = strlcpy(buf, def, buflen);
+		if (len >= buflen)
+			ret = ERANGE;
+		else {
+			ret = __itoa(num, sign, buf, len, buflen);
+			if (ret == 0)
+				ret = EINVAL;
+		}
+	}
+
+	return ret;
+}
+
+
+
+#define USIGPREFIX "Unknown signal: "
+
+char *
+__strsignal(int num, char *buf)
+{
+	__num2string(num, 0, 2, buf, NL_TEXTMAX, (char **)sys_siglist, NSIG,
+	    USIGPREFIX);
+	return buf;
+}
+#endif