diff --git a/lib/asn1/check-timegm.c b/lib/asn1/check-timegm.c
index 449ef5256..13d3abcf1 100644
--- a/lib/asn1/check-timegm.c
+++ b/lib/asn1/check-timegm.c
@@ -58,6 +58,15 @@ test_timegm(void)
     if (t != -1)
 	ret += 1;
 
+    _der_gmtime(1159696980, &tm);
+    if (tm.tm_year != 106 ||
+	tm.tm_mon != 9 ||
+	tm.tm_mday != 1 ||
+	tm.tm_hour != 10 ||
+	tm.tm_min != 3 ||
+	tm.tm_sec != 0)
+      errx(1, "tmtime failes");
+
     return ret;
 }
 
diff --git a/lib/asn1/der_locl.h b/lib/asn1/der_locl.h
index 0f65c50a2..a086e18fa 100644
--- a/lib/asn1/der_locl.h
+++ b/lib/asn1/der_locl.h
@@ -56,6 +56,7 @@
 #include "asn1-template.h"
 
 time_t _der_timegm (struct tm *);
+struct tm * _der_gmtime(time_t t, struct tm *);
 size_t _heim_len_unsigned (unsigned);
 size_t _heim_len_int (int);
 
diff --git a/lib/asn1/der_put.c b/lib/asn1/der_put.c
index c8192f25f..b8101458a 100644
--- a/lib/asn1/der_put.c
+++ b/lib/asn1/der_put.c
@@ -426,22 +426,22 @@ der_put_length_and_tag (unsigned char *p, size_t len, size_t len_val,
 int
 _heim_time2generalizedtime (time_t t, heim_octet_string *s, int gtimep)
 {
-     struct tm *tm;
+     struct tm tm;
      const size_t len = gtimep ? 15 : 13;
 
      s->data = malloc(len + 1);
      if (s->data == NULL)
 	 return ENOMEM;
      s->length = len;
-     tm = gmtime (&t);
+     _der_gmtime(t, &tm);
      if (gtimep)
 	 snprintf (s->data, len + 1, "%04d%02d%02d%02d%02d%02dZ",
-		   tm->tm_year + 1900, tm->tm_mon + 1, tm->tm_mday,
-		   tm->tm_hour, tm->tm_min, tm->tm_sec);
+		   tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
+		   tm.tm_hour, tm.tm_min, tm.tm_sec);
      else
 	 snprintf (s->data, len + 1, "%02d%02d%02d%02d%02d%02dZ",
-		   tm->tm_year % 100, tm->tm_mon + 1, tm->tm_mday,
-		   tm->tm_hour, tm->tm_min, tm->tm_sec);
+		   tm.tm_year % 100, tm.tm_mon + 1, tm.tm_mday,
+		   tm.tm_hour, tm.tm_min, tm.tm_sec);
 
      return 0;
 }
diff --git a/lib/asn1/libasn1-exports.def b/lib/asn1/libasn1-exports.def
index 3815917dc..6dfb93ea0 100644
--- a/lib/asn1/libasn1-exports.def
+++ b/lib/asn1/libasn1-exports.def
@@ -8,6 +8,7 @@ EXPORTS
 	SAMFlags2int
 	TicketFlags2int
 	_der_timegm
+	_der_gmtime
 	_heim_der_set_sort
 	_heim_fix_dce
 	_heim_len_int
diff --git a/lib/asn1/timegm.c b/lib/asn1/timegm.c
index c72968dc0..b56947841 100644
--- a/lib/asn1/timegm.c
+++ b/lib/asn1/timegm.c
@@ -42,6 +42,10 @@ is_leap(unsigned y)
     return (y % 4) == 0 && ((y % 100) != 0 || (y % 400) == 0);
 }
 
+static const unsigned ndays[2][12] ={
+    {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
+    {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};
+
 /*
  * This is a simplifed version of timegm(3) that doesn't accept out of
  * bound values that timegm(3) normally accepts but those are not
@@ -51,9 +55,6 @@ is_leap(unsigned y)
 time_t
 _der_timegm (struct tm *tm)
 {
-  static const unsigned ndays[2][12] ={
-    {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
-    {31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};
   time_t res = 0;
   unsigned i;
 
@@ -84,3 +85,37 @@ _der_timegm (struct tm *tm)
   res += tm->tm_sec;
   return res;
 }
+
+struct tm *
+_der_gmtime(time_t t, struct tm *tm)
+{
+    time_t secday = t % (3600 * 24);
+    time_t days = t / (3600 * 24);
+
+    memset(tm, 0, sizeof(*tm));
+
+    tm->tm_sec = secday % 60;
+    tm->tm_min = (secday % 3600) / 60;
+    tm->tm_hour = secday / 3600;
+
+    tm->tm_year = 70;
+    while(1) {
+	unsigned dayinyear = (is_leap(tm->tm_year) ? 366 : 365);
+	if (days < dayinyear)
+	    break;
+	tm->tm_year += 1;
+	days -= dayinyear;
+    }
+    tm->tm_mon = 0;
+
+    while (1) {
+	unsigned daysinmonth = ndays[is_leap(tm->tm_year)][tm->tm_mon];
+	if (days < daysinmonth)
+	    break;
+	days -= daysinmonth;
+	tm->tm_mon++;
+    }
+    tm->tm_mday = days + 1;
+
+    return tm;
+}