diff --git a/db/SQLiteClient.py b/db/SQLiteClient.py
index 068541c..d6e0481 100644
--- a/db/SQLiteClient.py
+++ b/db/SQLiteClient.py
@@ -45,9 +45,9 @@ def get_user_by_email(email: str):
 def update_user(id: int, name: str, email: str, password: str = None):
     now = datetime.now().isoformat()
     if password:
-        query = f"UPDATE users SET name = '{name}', email = '{email}', password = '{password}', updated_at = {now} WHERE id = {id};"
+        query = f"UPDATE users SET name = '{name}', email = '{email}', password = '{password}', updated_at = '{now}' WHERE id = {id};"
     else:
-        query = f"UPDATE users SET name = '{name}', email = '{email}', updated_at = {now} WHERE id = {id};"
+        query = f"UPDATE users SET name = '{name}', email = '{email}', updated_at = '{now}' WHERE id = {id};"
     conn = con3()
     cursor = conn.cursor()
     cursor.execute(query)
@@ -144,7 +144,7 @@ def get_slots(user_id: int):
 
 def update_slot(id: int, slot: int):
     now = datetime.now().isoformat()
-    query = f"UPDATE habits SET slot = {slot}, updated_at = {now} WHERE id = {id};"
+    query = f"UPDATE habits SET slot = {slot}, updated_at = '{now}' WHERE id = {id};"
     conn = con3()
     cursor = conn.cursor()
     cursor.execute(query)
@@ -155,7 +155,7 @@ def update_slot(id: int, slot: int):
 
 def update_habit(id: int, name: str, note: str, times: int, unit: int):
     now = datetime.now().isoformat()
-    query = f"UPDATE habits SET name = {name}, note = {note}, times = {times}, unit = {unit}, updated_at = {now} WHERE id = {id};"
+    query = f"UPDATE habits SET name = {name}, note = {note}, times = {times}, unit = {unit}, updated_at = '{now}' WHERE id = {id};"
     conn = con3()
     cursor = conn.cursor()
     cursor.execute(query)