diff --git a/lib/asn1/der_get.c b/lib/asn1/der_get.c
index f4d377789..022d705c1 100644
--- a/lib/asn1/der_get.c
+++ b/lib/asn1/der_get.c
@@ -289,6 +289,10 @@ der_get_heim_integer (const unsigned char *p, size_t len,
     return 0;
 }
 
+#ifndef HAVE_TIMEGM
+#define timegm(x) _der_timegm(x)
+#endif
+
 static int
 generalizedtime2time (const char *s, time_t *t)
 {
@@ -312,6 +316,7 @@ generalizedtime2time (const char *s, time_t *t)
     *t = timegm (&tm);
     return 0;
 }
+#undef timegm
 
 static int
 der_get_time (const unsigned char *p, size_t len, 
diff --git a/lib/asn1/timegm.c b/lib/asn1/timegm.c
index b4c39927d..c6b19e283 100644
--- a/lib/asn1/timegm.c
+++ b/lib/asn1/timegm.c
@@ -45,7 +45,7 @@ is_leap(unsigned y)
 }
 
 time_t
-timegm (struct tm *tm)
+_der_timegm (struct tm *tm)
 {
   static const unsigned ndays[2][12] ={
     {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},