diff --git a/include/wx/datetime.inl b/include/wx/datetime.inl
index 450a11fc13..10e929a22a 100644
--- a/include/wx/datetime.inl
+++ b/include/wx/datetime.inl
@@ -149,7 +149,7 @@ inline time_t wxDateTime::GetTicks() const
     return (time_t)((m_time / (long)TIME_T_FACTOR).GetLo())+WX_TIME_BASE_OFFSET ;
 }
 
-bool wxDateTime::SetToLastWeekDay(WeekDay weekday,
+inline bool wxDateTime::SetToLastWeekDay(WeekDay weekday,
                                          Month month,
                                          int year)
 {