diff --git a/src/lang/english.txt b/src/lang/english.txt
--- a/src/lang/english.txt
+++ b/src/lang/english.txt
@@ -564,8 +564,8 @@ STR_PERFORMANCE_DETAIL_TOTAL            
 STR_PERFORMANCE_DETAIL_VEHICLES_TOOLTIP                         :{BLACK}Number of vehicles that turned a profit last year; this includes road vehicles, trains, ships and aircraft
 STR_PERFORMANCE_DETAIL_STATIONS_TOOLTIP                         :{BLACK}Number of recently-serviced station parts. Every part of a station (e.g. train station, bus stop, airport) is counted, even if they are connected as one station
 STR_PERFORMANCE_DETAIL_MIN_PROFIT_TOOLTIP                       :{BLACK}The profit of the vehicle with the lowest income (only vehicles older than two years are considered)
-STR_PERFORMANCE_DETAIL_MIN_INCOME_TOOLTIP                       :{BLACK}Amount of cash made in the month with the lowest profit of the last 12 quarters
-STR_PERFORMANCE_DETAIL_MAX_INCOME_TOOLTIP                       :{BLACK}Amount of cash made in the month with the highest profit of the last 12 quarters
+STR_PERFORMANCE_DETAIL_MIN_INCOME_TOOLTIP                       :{BLACK}Amount of cash made in the quarter with the lowest profit of the last 12 quarters
+STR_PERFORMANCE_DETAIL_MAX_INCOME_TOOLTIP                       :{BLACK}Amount of cash made in the quarter with the highest profit of the last 12 quarters
 STR_PERFORMANCE_DETAIL_DELIVERED_TOOLTIP                        :{BLACK}Units of cargo delivered in the last four quarters
 STR_PERFORMANCE_DETAIL_CARGO_TOOLTIP                            :{BLACK}Number of types of cargo delivered in the last quarter
 STR_PERFORMANCE_DETAIL_MONEY_TOOLTIP                            :{BLACK}Amount of money this company has in the bank