diff --git a/api/api_v1/endpoints/query.py b/api/api_v1/endpoints/query.py
index 063f880..1cfc1ba 100644
--- a/api/api_v1/endpoints/query.py
+++ b/api/api_v1/endpoints/query.py
@@ -6,6 +6,7 @@ from urllib.parse import quote
 import pandas as pd
 import numpy as np
 from fastapi import APIRouter, Depends, Request
+from fastapi.encoders import jsonable_encoder
 from motor.motor_asyncio import AsyncIOMotorDatabase
 from fastapi.responses import StreamingResponse
 
@@ -356,9 +357,13 @@ async def retention_model(request: Request,
     tmp['d0'] = 0
     for rt, rd in retention_avg_dict.items():
         tmp['d0'] = tmp['d0'] + rd['cnt0']
-        tmp['p'].append(round(rd['cntn'] * 100 / rd['cnt0'], 2))
+        n = round(rd['cntn'] * 100 / rd['cnt0'],2)
+        n = 0 if np.isnan(n) else n
+        tmp['p'].append(n)
         tmp['n'].append(rd['cntn'])
-        tmp['p_outflow'].append(round(rd['o_cntn'] * 100 / rd['cnt0'], 2))
+        n = round(rd['o_cntn'] * 100 / rd['cnt0'],2)
+        n = 0 if np.isnan(n) else n
+        tmp['p_outflow'].append(n)
         tmp['n_outflow'].append(rd['o_cntn'])