diff -up syncevolution-1.5.1/src/syncevo/icaltz-util.c.libical2 syncevolution-1.5.1/src/syncevo/icaltz-util.c
--- syncevolution-1.5.1/src/syncevo/icaltz-util.c.libical2	2014-04-28 11:55:52.000000000 +0200
+++ syncevolution-1.5.1/src/syncevo/icaltz-util.c	2016-01-19 10:04:32.090379654 +0100
@@ -162,7 +162,7 @@ typedef struct
 } leap;
 
 #ifndef EVOLUTION_ICAL_COMPATIBILITY
-extern const char *ical_tzid_prefix;
+const char *ical_tzid_prefix = "/freeassociation.sourceforge.net/";
 #endif
 
 static int