--- a/browser/components/extensions/schemas/history.json
+++ b/browser/components/extensions/schemas/history.json
@@ -86,29 +86,16 @@
             "type": "string",
             "description": "The visit ID of the referrer."
           },
           "transition": {
             "$ref": "TransitionType",
             "description": "The $(topic:transition-types)[transition type] for this visit from its referrer."
           }
         }
-      },
-      {
-        "id": "HistoryTime",
-        "description": "A time specified as a Date object, a number or string representing milliseconds since the epoch, or an ISO 8601 string",
-        "choices": [
-          {
-            "type": "string",
-            "pattern": "^[1-9]\\d*$"
-          },
-          {
-            "$ref": "extensionTypes.Date"
-          }
-        ]
       }
     ],
     "functions": [
       {
         "name": "search",
         "type": "function",
         "description": "Searches the history for the last visit time of each page matching the query.",
         "async": "callback",
@@ -117,22 +104,22 @@
             "name": "query",
             "type": "object",
             "properties": {
               "text": {
                 "type": "string",
                 "description": "A free-text query to the history service.  Leave empty to retrieve all pages."
               },
               "startTime": {
-                "$ref": "HistoryTime",
+                "$ref": "extensionTypes.Date",
                 "optional": true,
                 "description": "Limit results to those visited after this date. If not specified, this defaults to 24 hours in the past."
               },
               "endTime": {
-                "$ref": "HistoryTime",
+                "$ref": "extensionTypes.Date",
                 "optional": true,
                 "description": "Limit results to those visited before this date."
               },
               "maxResults": {
                 "type": "integer",
                 "optional": true,
                 "minimum": 1,
                 "description": "The maximum number of results to retrieve.  Defaults to 100."
@@ -205,17 +192,17 @@
                 "description": "The title of the page."
               },
               "transition": {
                 "$ref": "TransitionType",
                 "optional": true,
                 "description": "The $(topic:transition-types)[transition type] for this visit from its referrer."
               },
               "visitTime": {
-                "$ref": "HistoryTime",
+                "$ref": "extensionTypes.Date",
                 "optional": true,
                 "description": "The date when this visit occurred."
               }
             }
           },
           {
             "name": "callback",
             "type": "function",
@@ -254,21 +241,21 @@
         "description": "Removes all items within the specified date range from the history.  Pages will not be removed from the history unless all visits fall within the range.",
         "async": "callback",
         "parameters": [
           {
             "name": "range",
             "type": "object",
             "properties": {
               "startTime": {
-                "$ref": "HistoryTime",
+                "$ref": "extensionTypes.Date",
                 "description": "Items added to history after this date."
               },
               "endTime": {
-                "$ref": "HistoryTime",
+                "$ref": "extensionTypes.Date",
                 "description": "Items added to history before this date."
               }
             }
           },
           {
             "name": "callback",
             "type": "function",
             "parameters": []

--- a/browser/components/extensions/test/xpcshell/test_ext_history.js
+++ b/browser/components/extensions/test/xpcshell/test_ext_history.js
@@ -284,17 +284,16 @@ add_task(function* test_add_url() {
 
     browser.test.sendMessage("ready");
   }
 
   let addTestData = [
     [{}, "default"],
     [{visitTime: new Date()}, "with_date"],
     [{visitTime: Date.now()}, "with_ms_number"],
-    [{visitTime: Date.now().toString()}, "with_ms_string"],
     [{visitTime: new Date().toISOString()}, "with_iso_string"],
     [{transition: "typed"}, "valid_transition"],
   ];
 
   let failTestData = [
     [{transition: "generated"}, "an invalid transition", "|generated| is not a supported transition for history"],
     [{visitTime: Date.now() + 1000000}, "a future date", "cannot be a future date"],
     [{url: "about.config"}, "an invalid url", "about.config is not a valid URL"],