diff --git a/mozilla/calendar/base/src/maketzdata.pl b/mozilla/calendar/base/src/maketzdata.pl
index 4df9286872b..b498c07351a 100644
--- a/mozilla/calendar/base/src/maketzdata.pl
+++ b/mozilla/calendar/base/src/maketzdata.pl
@@ -167,7 +167,7 @@ print TZDATA <<EOF
 };
 
 // needed for implementing calIICSService.tzIdPrefix
-NS_NAMED_LITERAL_CSTRING(gTzIdPrefix, "${TZ_PREFIX}");
+NS_NAMED_LITERAL_CSTRING(gTzIdPrefix, "${TZ_PREFIX}/");
 EOF
 ;
 
diff --git a/mozilla/calendar/base/src/tzdata.c b/mozilla/calendar/base/src/tzdata.c
index c8d333c392b..a8ced266e7f 100644
--- a/mozilla/calendar/base/src/tzdata.c
+++ b/mozilla/calendar/base/src/tzdata.c
@@ -2435,4 +2435,4 @@ static ical_timezone_data_struct ical_timezone_data[] = {
 };
 
 // needed for implementing calIICSService.tzIdPrefix
-NS_NAMED_LITERAL_CSTRING(gTzIdPrefix, "/mozilla.org/20070129_1");
+NS_NAMED_LITERAL_CSTRING(gTzIdPrefix, "/mozilla.org/20070129_1/");