diff --git a/src/preferences/time/CalendarView.cpp b/src/preferences/time/CalendarView.cpp
index 840325e8dc..b6a4ee912e 100644
--- a/src/preferences/time/CalendarView.cpp
+++ b/src/preferences/time/CalendarView.cpp
@@ -393,7 +393,7 @@ TCalendarView::InitDates()
 	
 	int32 label = 0;
 	int idx = 0;
-	f_firstday = getFirstDay(f_month+1, f_year);
+	f_firstday = getFirstDay(f_month, f_year);
 	int daycnt = getDaysInMonth(f_month, f_year);
 	bool cday = false;
 	for (int row = 0; row < 6; row++) {
@@ -403,7 +403,8 @@ TCalendarView::InitDates()
 			if (idx < f_firstday || idx > daycnt +f_firstday +1)
 				label = 0;
 			else
-				label = idx -(f_firstday +1);
+				label = idx - (f_firstday - 1);
+			
 			idx++;
 			cday = label == f_day;
 			day->SetTo(label, cday);
@@ -441,7 +442,7 @@ TCalendarView::SetTo(int32 year, int32 month, int32 day)
 		InitDates();
 	} else if (f_day != day) {
 		f_day = day;
-		int idx = ((f_day/7)*7) + (f_day%7 +f_firstday +1);
+		int idx = ((f_day/7)*7) + (f_day%7 +f_firstday - 1);
 		TDay *day = dynamic_cast<TDay *>(ChildAt(idx));
 		f_cday->SetValue(B_CONTROL_OFF);
 		f_cday = day;
diff --git a/src/preferences/time/DateUtils.cpp b/src/preferences/time/DateUtils.cpp
index 19ca670fa3..661a25bc6d 100644
--- a/src/preferences/time/DateUtils.cpp
+++ b/src/preferences/time/DateUtils.cpp
@@ -1,6 +1,8 @@
 #include "DateUtils.h"
 #include "math.h"
 
+#include <time.h>
+
 bool
 isLeapYear(const int year)
 {
@@ -28,26 +30,19 @@ getDaysInMonth(const int month, const int year)
 int
 getFirstDay(const int month, const int year)
 {
-	int l_century = year/100;
-	int l_decade = year%100;
-	int l_month = (month +10)%12;
-	int l_day = 1;
+	struct tm tm;
+	time_t currentTime = time(NULL);
+	localtime_r(&currentTime, &tm);
 	
-	if (l_month == 1 || l_month == 2) {
-		if (l_decade == 0) {
-			l_decade = 99;
-			l_century -= 1;
-		} else
-		 l_decade-= 1;
-	}
+	// TODO: review this.
+	// We rely on the fact that tm.tm_wday is calculated
+	// starting from the following parameters
+	tm.tm_mon = month;
+	tm.tm_year = year;
+	tm.tm_mday = 1;
 	
-	float tmp = (l_day +(floor(((13 *l_month) -1)/5)) 
-		+l_decade +(floor(l_decade /4)) 
-		+(floor(l_century/4)) -(2 *l_century));
-	int result = static_cast<int>(tmp)%7;
-	
-	if (result < 0)
-		result += 7;
+	currentTime = mktime(&tm);
+	localtime_r(&currentTime, &tm);
 		
-	return result;
+	return tm.tm_wday;
 }