Merge rows based on index

I have a pandas dataframe like this,

Timestamp Meter1 Meter2
0         234    NaN
1         235    NaN
2         236    NaN
0         NaN    100
1         NaN    101
2         NaN    102

and I'm having trouble merging the rows based on the index Timestamp to something like this,

Timestamp Meter1 Meter2
0         234    100
1         235    101
2         236    102