Wemo Binding, discovery and UFW

Can someone help me with UFW on my Pi to allow auto discovery of Wemo devices by the Wemo binding? I had to disable UFW to get it working, and I’d like to put the relevant rule in UFW to allow auto discovery to work in future.
In the log I see
IN=eth0 OUT= MAC= SRC=DST= LEN=438 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=3076 DPT=1901 LEN=418
Presumably I need to allow UDP incoming from the local network, but which port ranges?