diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4e8671045..8ae7223e5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -76,6 +76,7 @@
 - `max_travel_time` not accounted for with vehicle steps in solving mode (#954)
 - `max_travel_time` not accounted for in `RouteSplit` (#941)
 - Wrong capacity checks in `RouteSplit` (#981)
+- Overflow related to scaling default time windows (#1020)
 
 #### Internals
 
diff --git a/src/structures/typedefs.h b/src/structures/typedefs.h
index 79ef1ec15..ed70b0e5f 100644
--- a/src/structures/typedefs.h
+++ b/src/structures/typedefs.h
@@ -190,19 +190,22 @@ struct StringHash {
 };
 
 namespace utils {
-inline Duration scale_from_user_duration(UserDuration d) {
+constexpr inline Duration scale_from_user_duration(UserDuration d) {
   return DURATION_FACTOR * static_cast<Duration>(d);
 }
 
-inline UserDuration scale_to_user_duration(Duration d) {
+constexpr inline UserDuration scale_to_user_duration(Duration d) {
+  assert(d <=
+         scale_from_user_duration(std::numeric_limits<UserDuration>::max()));
   return static_cast<UserDuration>(d / DURATION_FACTOR);
 }
 
-inline Cost scale_from_user_cost(UserCost c) {
+constexpr inline Cost scale_from_user_cost(UserCost c) {
   return DURATION_FACTOR * COST_FACTOR * static_cast<Cost>(c);
 }
 
-inline UserCost scale_to_user_cost(Cost c) {
+constexpr inline UserCost scale_to_user_cost(Cost c) {
+  assert(c <= scale_from_user_cost(std::numeric_limits<UserCost>::max()));
   return static_cast<UserCost>(c / (DURATION_FACTOR * COST_FACTOR));
 }
 } // namespace utils
diff --git a/src/structures/vroom/time_window.cpp b/src/structures/vroom/time_window.cpp
index 69832f78a..487526c68 100644
--- a/src/structures/vroom/time_window.cpp
+++ b/src/structures/vroom/time_window.cpp
@@ -13,10 +13,13 @@ All rights reserved (see LICENSE).
 namespace vroom {
 
 constexpr Duration TimeWindow::default_length =
-  std::numeric_limits<Duration>::max();
+  utils::scale_from_user_duration(std::numeric_limits<UserDuration>::max());
 
 TimeWindow::TimeWindow()
-  : start(0), end(std::numeric_limits<Duration>::max()), length(end - start) {
+  : start(0),
+    end(utils::scale_from_user_duration(
+      std::numeric_limits<UserDuration>::max())),
+    length(end - start) {
 }
 
 TimeWindow::TimeWindow(UserDuration start, UserDuration end)