diff -up libical-2.0.0/src/libical/icalrecur.c.arm libical-2.0.0/src/libical/icalrecur.c
--- libical-2.0.0/src/libical/icalrecur.c.arm	2016-01-18 15:37:30.117898162 +0100
+++ libical-2.0.0/src/libical/icalrecur.c	2016-01-18 15:37:36.730897882 +0100
@@ -491,8 +491,8 @@ static int icalrecur_add_bydayrules(stru
 
     while (n != 0) {
         int sign = 1;
-        char weekno;  /* note: Novell/Groupwise sends BYDAY=255SU,
-                         so we fit in a signed char to get -1 SU for last Sun */
+        signed char weekno;  /* note: Novell/Groupwise sends BYDAY=255SU,
+                                so we fit in a signed char to get -1 SU for last Sun */
         icalrecurrencetype_weekday wd;
 
         if (i == ICAL_BY_DAY_SIZE) {
@@ -510,7 +510,7 @@ static int icalrecur_add_bydayrules(stru
         }
 
         /* Get Optional weekno */
-        weekno = (char)strtol(t, &t, 10);
+        weekno = (signed char)strtol(t, &t, 10);
         if (weekno < 0) {
             weekno = -weekno;
             sign = -1;