mixing 3.3 and 5V on I2C bus isn't really a great idea - you could try pulling up to 3.8V (4.7k pull up to 5V, 15k to gnd) - this should be high enough to work with most 5V inputs yet not take 3.3 inputs too high.
mixing 3.3 and 5V on I2C bus isn't really a great idea - you could try pulling up to 3.8V (4.7k pull up to 5V, 15k to gnd) - this should be high enough to work with most 5V inputs yet not take 3.3 inputs too high.