diff -up libical-1.0.1/src/libical/icaltime.c.avoid-putenv libical-1.0.1/src/libical/icaltime.c
--- libical-1.0.1/src/libical/icaltime.c.avoid-putenv	2014-10-09 17:07:05.000000000 +0200
+++ libical-1.0.1/src/libical/icaltime.c	2015-01-26 11:56:35.153309240 +0100
@@ -64,11 +64,6 @@
 #define gmtime_r(tp,tmp) (gmtime(tp)?(*(tmp)=*gmtime(tp),(tmp)):0)
 #endif
 
-#ifdef HAVE_PTHREAD
- #include <pthread.h>    
-    static pthread_mutex_t tzid_mutex = PTHREAD_MUTEX_INITIALIZER;
-#endif
-
 /*
  *  Function to convert a struct tm time specification
  *  to an ANSI time_t using the specified time zone.
@@ -77,7 +72,7 @@
  *  local daylight savings time applied to the result.
  *  This function expects well-formed input.
  */
-static time_t make_time(struct tm *tm, int tzm)
+static time_t make_time(struct tm *tm, int tzm, int be_strict)
 {
   time_t tim;
 
@@ -91,13 +86,13 @@ static time_t make_time(struct tm *tm, i
 #if (SIZEOF_TIME_T == 4)
   /* check that year specification within range */
 
-  if (tm->tm_year < 70 || tm->tm_year > 138)
+  if (be_strict && (tm->tm_year < 70 || tm->tm_year > 138))
     return((time_t) -1);
 
   /* check for upper bound of Jan 17, 2038 (to avoid possibility of
      32-bit arithmetic overflow) */
   
-  if (tm->tm_year == 138) {
+  if (be_strict && tm->tm_year == 138) {
     if (tm->tm_mon > 0)
       return((time_t) -1);
     else if (tm->tm_mday > 17)
@@ -291,99 +286,12 @@ time_t icaltime_as_timet(const struct ic
     stm.tm_year = tt.year-1900;
     stm.tm_isdst = -1;
 
-    t = make_time(&stm, 0);
+    t = make_time(&stm, 0, 1);
 
     return t;
 
 }
 
-
-/* Structure used by set_tz to hold an old value of TZ, and the new
-   value, which is in memory we will have to free in unset_tz */
-/* This will hold the last "TZ=XXX" string we used with putenv(). After we
-   call putenv() again to set a new TZ string, we can free the previous one.
-   As far as I know, no libc implementations actually free the memory used in
-   the environment variables (how could they know if it is a static string or
-   a malloc'ed string?), so we have to free it ourselves. */
-static char* saved_tz = NULL;
-
-/* If you use set_tz(), you must call unset_tz() some time later to restore the
-   original TZ. Pass unset_tz() the string that set_tz() returns. Call both the functions
-   locking the tzid mutex as in icaltime_as_timet_with_zone */
-char* set_tz(const char* tzid)
-{
-    char *old_tz, *old_tz_copy = NULL, *new_tz;
-
-    /* Get the old TZ setting and save a copy of it to return. */
-    old_tz = getenv("TZ");
-    if(old_tz){
-	old_tz_copy = (char*)malloc(strlen (old_tz) + 4);
-
-	if(old_tz_copy == 0){
-	    icalerror_set_errno(ICAL_NEWFAILED_ERROR);
-	    return 0;
-	}
-
-	strcpy (old_tz_copy, "TZ=");
-	strcpy (old_tz_copy + 3, old_tz);
-    }
-
-    /* Create the new TZ string. */
-    new_tz = (char*)malloc(strlen (tzid) + 4);
-
-    if(new_tz == 0){
-	icalerror_set_errno(ICAL_NEWFAILED_ERROR);
-	free(old_tz_copy);
-	return 0;
-    }
-
-    strcpy (new_tz, "TZ=");
-    strcpy (new_tz + 3, tzid);
-
-    /* Add the new TZ to the environment. */
-    putenv(new_tz); 
-
-    /* Free any previous TZ environment string we have used in a synchronized manner. */
-
-    free (saved_tz);
-
-    /* Save a pointer to the TZ string we just set, so we can free it later. */
-    saved_tz = new_tz;
-
-    return old_tz_copy; /* This will be zero if the TZ env var was not set */
-}
-
-void unset_tz(char *tzstr)
-{
-    /* restore the original environment */
-
-    if(tzstr!=0){
-	putenv(tzstr);
-    } else {
-	/* Delete from environment.  We prefer unsetenv(3) over putenv(3)
-	   because the former is POSIX and behaves consistently.  The later
-	   does not unset the variable in some systems (like NetBSD), leaving
-	   it with an empty value.  This causes problems later because further
-	   calls to time related functions in libc will treat times in UTC. */
-#ifdef HAVE_UNSETENV
-	unsetenv("TZ");
-#else
-#ifdef _MSC_VER 
-	putenv("TZ="); // The equals is required to remove with MS Visual C++
-#else
-	putenv("TZ");
-#endif
-#endif
-    } 
-
-    /* Free any previous TZ environment string we have used in a synchronized manner */
-    free (saved_tz);
-
-    /* Save a pointer to the TZ string we just set, so we can free it later.
-       (This can possibly be NULL if there was no TZ to restore.) */
-    saved_tz = tzstr;
-}
-
 /**	Return the time as seconds past the UNIX epoch, using the
  *	given timezone.
  *
@@ -397,8 +305,6 @@ time_t icaltime_as_timet_with_zone(const
 {
     icaltimezone *utc_zone;
     struct tm stm;
-    time_t t;
-    char *old_tz;
     struct icaltimetype local_tt;
     
     utc_zone = icaltimezone_get_utc_timezone ();
@@ -426,25 +332,8 @@ time_t icaltime_as_timet_with_zone(const
     stm.tm_mon = local_tt.month-1;
     stm.tm_year = local_tt.year-1900;
     stm.tm_isdst = -1;
-/* The functions putenv and mktime are not thread safe, inserting a lock
-to prevent any crashes */
 
-#ifdef HAVE_PTHREAD
-    pthread_mutex_lock (&tzid_mutex);
-#endif
-    
-    /* Set TZ to UTC and use mktime to convert to a time_t. */
-    old_tz = set_tz ("UTC");
-    tzset ();
-
-    t = mktime (&stm);
-    unset_tz (old_tz);
-    tzset ();
-
-#ifdef HAVE_PTHREAD
-    pthread_mutex_unlock (&tzid_mutex);
-#endif
-    return t;
+    return make_time (&stm, 0, 0);
 }
 
 const char* icaltime_as_ical_string(const struct icaltimetype tt)