diff --git a/ts/session/constants.ts b/ts/session/constants.ts
index 73f5eee1f..70fbb4ff7 100644
--- a/ts/session/constants.ts
+++ b/ts/session/constants.ts
@@ -1,13 +1,18 @@
-import { NumberUtils } from './utils';
+import { DAYS, HOURS, MINUTES } from './utils/Number';
+// tslint:disable: binary-expression-operand-order
 
-// Default TTL
+/**
+ * FIXME The -1 hours is a hack to make the PN not trigger a Notification for those control message.
+ * Apple devices must show a Notification if a PN is received, and for those
+ * control message, there is nothing to display (yet).
+ */
 export const TTL_DEFAULT = {
-  PAIRING_REQUEST: NumberUtils.timeAsMs(2, 'minutes'),
-  DEVICE_UNPAIRING: NumberUtils.timeAsMs(4 * 24 - 1, 'hours'),
-  SESSION_REQUEST: NumberUtils.timeAsMs(4 * 24 - 1, 'hours'),
-  SESSION_ESTABLISHED: NumberUtils.timeAsMs(2 * 24 - 1, 'hours'),
-  END_SESSION_MESSAGE: NumberUtils.timeAsMs(4 * 24 - 1, 'hours'),
-  TYPING_MESSAGE: NumberUtils.timeAsMs(1, 'minute'),
-  ONLINE_BROADCAST: NumberUtils.timeAsMs(1, 'minute'),
-  REGULAR_MESSAGE: NumberUtils.timeAsMs(2, 'days'),
+  PAIRING_REQUEST: 2 * MINUTES,
+  DEVICE_UNPAIRING: 4 * DAYS - 1 * HOURS,
+  SESSION_REQUEST: 4 * DAYS - 1 * HOURS,
+  SESSION_ESTABLISHED: 2 * DAYS - 1 * HOURS,
+  END_SESSION_MESSAGE: 4 * DAYS - 1 * HOURS,
+  TYPING_MESSAGE: 1 * MINUTES,
+  ONLINE_BROADCAST: 1 * MINUTES,
+  REGULAR_MESSAGE: 2 * DAYS,
 };
diff --git a/ts/session/utils/Number.ts b/ts/session/utils/Number.ts
index bc4f4267f..0948dcd67 100644
--- a/ts/session/utils/Number.ts
+++ b/ts/session/utils/Number.ts
@@ -8,24 +8,10 @@ type TimeUnit =
   | 'day'
   | 'days';
 
-export const timeAsMs = (value: number, unit: TimeUnit) => {
-  // Converts a time to milliseconds
-  // Valid units: second, minute, hour, day
-  const unitAsSingular = unit.replace(new RegExp('s?$'), '');
-
-  switch (unitAsSingular) {
-    case 'second':
-      return value * 1000;
-    case 'minute':
-      return value * 60 * 1000;
-    case 'hour':
-      return value * 60 * 60 * 1000;
-    case 'day':
-      return value * 24 * 60 * 60 * 1000;
-    default:
-      return value;
-  }
-};
+export const MINUTES = 60 * 1000; // in ms
+// tslint:disable: binary-expression-operand-order
+export const HOURS = 60 * MINUTES; // in ms
+export const DAYS = 24 * HOURS; // in ms
 
 export const msAsUnit = (value: number, unit: TimeUnit) => {
   // Converts milliseconds to your preferred unit