In accordance with one or more embodiments herein, a flame detecting arrangement 100 is provided. The flame detecting arrangement 100 comprises: at least one optical flame detector 110, arranged with its field-of-view covering a predetermined area; at least one movement sensor 120, arranged together with the at least one flame detector 110; and at least one processing device 180 arranged together with the at least one flame detector 110. The at least one processing device 180 is arranged to: receive signals from the movement sensor 120; detect abnormal movement of the flame detector 110 based on these signals; and alert an operator and/or a control system 200 if abnormal movement of the flame detector 110 has been detected. This enables the field-of-view of the flame detector to be corrected to the desired, preferably the original, field-of-view.