--- a/dom/alarm/AlarmService.jsm
+++ b/dom/alarm/AlarmService.jsm
@@ -389,16 +389,23 @@ this.AlarmService = {
     aErrorCb = aErrorCb || function() {};
 
     if (!aNewAlarm) {
       aErrorCb("alarm is null");
       return;
     }
 
     aNewAlarm['timezoneOffset'] = this._currentTimezoneOffset;
+    let aNewAlarmTime = this._getAlarmTime(aNewAlarm);
+    if (aNewAlarmTime <= Date.now()) {
+      debug("Adding a alarm that has past time.");
+      this._debugCurrentAlarm();
+      aErrorCb("InvalidStateError");
+      return;
+    }
 
     this._db.add(
       aNewAlarm,
       function addSuccessCb(aNewId) {
         debug("Callback after adding alarm in database.");
 
         aNewAlarm['id'] = aNewId;
 
@@ -412,17 +419,16 @@ this.AlarmService = {
           this._debugCurrentAlarm();
           aSuccessCb(aNewId);
           return;
         }
 
         // If the new alarm is earlier than the current alarm, swap them and
         // push the previous alarm back to queue.
         let alarmQueue = this._alarmQueue;
-        let aNewAlarmTime = this._getAlarmTime(aNewAlarm);
         let currentAlarmTime = this._getAlarmTime(this._currentAlarm);
         if (aNewAlarmTime < currentAlarmTime) {
           alarmQueue.unshift(this._currentAlarm);
           this._currentAlarm = aNewAlarm;
           this._debugCurrentAlarm();
           aSuccessCb(aNewId);
           return;
         }

--- a/dom/alarm/test/test_alarm_add_date.html
+++ b/dom/alarm/test/test_alarm_add_date.html
@@ -52,21 +52,21 @@
     } catch (e) {
       ok(false,
          "Unexpected exception trying to add alarm for yesterday.");
       return testNull();
     }
     domRequest.onsuccess = function(e) {
       navigator.mozAlarms.remove(e.target.result);
 
-      ok(true, "Should be able to add alarm for already past date, which should fire immediately.");
+      ok(false, "Should not be able to add alarm for already past date.");
       testNull();
     };
     domRequest.onerror = function(e) {
-      ok(false, "Unable to add alarm for yesterday.");
+      ok(true, "Can't use past date when adding new alarm.");
 
       // Errors as it should, on to the next test
       testNull();
     }
   }
 
   // Verify passing null does indeed fail
   function testNull() {