diff --git a/plugins/statistics.koplugin/main.lua b/plugins/statistics.koplugin/main.lua
index 733668a6b..87b723f34 100755
--- a/plugins/statistics.koplugin/main.lua
+++ b/plugins/statistics.koplugin/main.lua
@@ -405,10 +405,14 @@ function ReaderStatistics:onPageUpdate(pageno)
             self.current_period = self.current_period + diff_time
             self.data.total_time_in_sec = self.data.total_time_in_sec + diff_time
             self.data.performance_in_pages[curr_time.sec] = pageno
+            -- we cannot save stats each time this is a page update event,
+            -- because the self.data may not even be initialized when such a event
+            -- comes, which will render a blank stats written into doc settings
+            -- and all previous stats are totally wiped out.
+            self.ui.doc_settings:saveSetting("stats", self.data)
         end
 
         self.last_time = curr_time
-        self.ui.doc_settings:saveSetting("stats", self.data)
     end
 end
 
@@ -486,6 +490,7 @@ function ReaderStatistics:saveSettings(fields)
 end
 
 function ReaderStatistics:onReadSettings(config)
+    -- delay initialization for accurate total pages count of the doc
     UIManager:scheduleIn(0.1, function() self:initData(config) end)
 end
 
diff --git a/spec/unit/readerfooter_spec.lua b/spec/unit/readerfooter_spec.lua
index 24e0ecaf0..865f030f3 100644
--- a/spec/unit/readerfooter_spec.lua
+++ b/spec/unit/readerfooter_spec.lua
@@ -13,7 +13,8 @@ describe("Readerfooter module", function()
         readerui.view.footer.settings.all_at_once = true
         readerui.view.footer:updateFooterPage()
         timeinfo = readerui.view.footer:getTimeInfo()
-        assert.are.same('B:0% | '..timeinfo..' | 1 / 1 | => 0 | R:100% | TB: 00:00 | TC: 00:00',
+        -- stats has not been initialized here, so we get na TB and TC
+        assert.are.same('B:0% | '..timeinfo..' | 1 / 1 | => 0 | R:100% | TB: na | TC: na',
                         readerui.view.footer.progress_text.text)
     end)