inconsistent types in google earth engine with Export.image.toDrive()

I have computed NDVI from Landsat7 image, but when I want to export the result in google drive with Export.image.toDrive() it failed with the message error : Fail with an error : Error: Exported bands must have compatible data types; found inconsistent types: Float32 and Float64.

How can I overpass this issue ?

/*-------------------------------------------------------------
                             FUNCTION
-------------------------------------------------------------*/

// This function adds a band representing the image timestamp.
var addTime = function(image) {

  return image.addBands(image.metadata('system:time_start')
    .divide(1000 * 60 * 60 * 24 * 365));
};

// COMPUTE NDVI OVER A COLLECTION FUNCTION
var addNDVI = function(image) {
  var ndvi = image.normalizedDifference(['B4', 'B3']).rename('NDVI');
  return image.addBands(ndvi);
};



/*-------------------------------------------------------------
                             END
-------------------------------------------------------------*/

//2001
var img2001 = ee.Image("LANDSAT/LE7_L1T/LE72040492001066EDC00").clip(zone_travail);

var withNDVI = addNDVI(img2001).select('NDVI');
var withNDVI = addTime(withNDVI);


print(withNDVI);


/*------------------------------------------------------------------------------------------
                                  SAVE DATA IN MY DRIVE 
--------------------------------------------------------------------------------------------*/


Export.image.toDrive({

  image: withNDVI,
  description: 'ls7_ndvi_2001',
  scale: 30,
  region: zone_travail
});

Answer

Cast the whole darn thing to a 32-bit float: withNDVI.float(). Of course, make sure you're not getting any overflow, but looks safe here.