diff --git a/circuitpython/code/cameteo.py b/circuitpython/code/cameteo.py
index f91df6f..99c19d8 100644
--- a/circuitpython/code/cameteo.py
+++ b/circuitpython/code/cameteo.py
@@ -426,7 +426,7 @@ def set_clock_from_localtime(clock, threshold=2.0, debug=False):
         print(err)
         print("Local time source : " + TIME_FORMAT.format(*time.localtime()[0:6]))
         print("Wait some time to have proper time from time source...")
-        return 1
+        return False
 
     # Max difference between GPS and internal RTC (in seconds):
     if abs(local_seconds - time.mktime(clock.datetime)) >= threshold:
@@ -435,4 +435,4 @@ def set_clock_from_localtime(clock, threshold=2.0, debug=False):
         clock.datetime = time.localtime()  # Trust localtime if there is a bias
         print("Clocks synced !")
 
-    return 0
+    return True
diff --git a/circuitpython/code/main.py b/circuitpython/code/main.py
index 3498141..03d1f8f 100644
--- a/circuitpython/code/main.py
+++ b/circuitpython/code/main.py
@@ -41,12 +41,12 @@ TODO for v1 :
  * send data through UART (work-in-progress)
 """
 __author__ = "arofarn"
-__version__ = 0.2
+__version__ = 0.3
 
 #######################
 import time
-import rtc
 import gc
+import rtc
 import board
 from busio import UART
 # import micropython
@@ -95,8 +95,8 @@ gps_data = cameteo.GPSData(debug=False)
 
 data = [sys_data, gps_data, bme_data]
 
-rtc.set_time_source(gps_data, debug=True)
-
+rtc.set_time_source(gps_data)
+CLOCK_SYNCED = False
 
 #############
 # Main loop #
@@ -108,16 +108,16 @@ while True:
 
     for src in data:
         src.update(current_time, verbose=PRINT_DATA)
-        cameteo.set_clock_from_localtime(CLOCK, threshold=2.0)
+
+    # Sync clocks
+    CLOCK_SYNCED = cameteo.set_clock_from_localtime(CLOCK, threshold=2.0, debug=True)
 
     for src in data:
-        src.write_on_flash(current_time)
+        #Only write data when clocks are OK
+        if CLOCK_SYNCED:
+            src.write_on_flash(current_time)
         src.send_json(current_time, uart=rpi_uart, verbose=True)
 
-    #     # First check if files need to rotate
-    #     last_rotation = rotate_files(last_rotation)
-
-
         gc.collect()
         # micropython.mem_info(1)
         # print('Memory free: {} allocated: {}'.format(gc.mem_free(), gc.mem_alloc()))