diff --git a/HTS_etf.py b/HTS_etf.py
index 2f84234..a96ef92 100644
--- a/HTS_etf.py
+++ b/HTS_etf.py
@@ -131,11 +131,11 @@ class HTS_etf (HTS):
         slow_k_week, slow_k_month = -1, -1
         self.cursor_stock.execute('select stochastic_slow_k, max(ymd) from stock_analysis_weekly where code=? group by 1 order by ymd desc', (stock_code, ))
         items = self.cursor_stock.fetchone()
-        if len(items)>0:
+        if items is not None and len(items)>0:
             slow_k_week = items[0]
         self.cursor_stock.execute('select stochastic_slow_k, max(ymd) from stock_analysis_monthly where code=? group by 1 order by ymd desc', (stock_code, ))
         items = self.cursor_stock.fetchone()
-        if len(items)>0:
+        if items is not None and len(items)>0:
             slow_k_month = items[0]
 
         return slow_k_week, slow_k_month
diff --git a/HTS_stocks.py b/HTS_stocks.py
index 581258d..d742d19 100644
--- a/HTS_stocks.py
+++ b/HTS_stocks.py
@@ -119,11 +119,11 @@ class HTS_Stocks (HTS):
         slow_k_week, slow_k_month = -1, -1
         self.cursor_stock.execute('select stochastic_slow_k, max(ymd) from stock_analysis_weekly where code=? group by 1 order by ymd desc', (stock_code, ))
         items = self.cursor_stock.fetchone()
-        if len(items)>0:
+        if items is not None and len(items)>0:
             slow_k_week = items[0]
         self.cursor_stock.execute('select stochastic_slow_k, max(ymd) from stock_analysis_monthly where code=? group by 1 order by ymd desc', (stock_code, ))
         items = self.cursor_stock.fetchone()
-        if len(items)>0:
+        if items is not None and len(items)>0:
             slow_k_month = items[0]
 
         return slow_k_week, slow_k_month