MYSQL trigger before update with iff

Question

I need to update the ESDUpdate with Today's Date whenever ESDDATE is updated.

This code is updating the ESDUpdate on ALL updates instead of just where the ESDDate is updated.

What can I do different?

BEFORE UPDATE ON `rhi_sap`.`dispatch_local`
FOR EACH ROW
-- Edit trigger body code below this line. Do not edit lines above this one
BEGIN
SET NEW.dbChangeDate = NOW();

IF NEW.ESDDate IS NOT NULL Then
SET NEW.ESDUpdate = CURDATE();
End IF;

END$$