diff --git a/docker-resources/plumber.R b/docker-resources/plumber.R
index 816bb02..3f3ce26 100644
--- a/docker-resources/plumber.R
+++ b/docker-resources/plumber.R
@@ -146,7 +146,7 @@ function(
       model_version = ml_model_version,
       start_date = start_of_week,
       end_date = end_of_week,
-      week = clock::date_format(clock::add_weeks(week_start(rtc_date), -1), format="%Y-W%U"),
+      week = get_week_number(rtc_date),
       .keep = "unused"
     )
   
@@ -163,7 +163,7 @@ function(
       model_version = ml_model_version,
       start_date = start_of_week,
       end_date = end_of_week,
-      week = clock::date_format(clock::add_weeks(week_start(rtc_date), -1), format="%Y-W%U"),
+      week = get_week_number(rtc_date),
       .keep = "unused"
     )
   
@@ -195,6 +195,12 @@ week_end <- function(date) {
   clock::date_ceiling(date, "week", origin = as.Date("1970-01-04"))
 }
 
+get_week_number <- function(date) {
+  previous_week <- clock::add_weeks(week_start(date), -1)
+  ywd <- clock::as_iso_year_week_day(previous_week)
+  paste0(clock::get_year(ywd), "-W", clock::get_week(ywd))
+}
+
 adult_risk_threshold_query <- 
   "select
     'Medium Risk' as risk,