diff --git a/biz.ganttproject.core/src/biz/ganttproject/core/calendar/GPCalendarBase.java b/biz.ganttproject.core/src/biz/ganttproject/core/calendar/GPCalendarBase.java
index f14c7939bf..c65581622a 100644
--- a/biz.ganttproject.core/src/biz/ganttproject/core/calendar/GPCalendarBase.java
+++ b/biz.ganttproject.core/src/biz/ganttproject/core/calendar/GPCalendarBase.java
@@ -32,20 +32,23 @@ of the License, or (at your option) any later version.
  * @author bard
  */
 abstract class GPCalendarBase implements GPCalendarCalc {
+
+  static final int MAX_WEEKEND_DAYS = 7;
+
   private final List<GPCalendarListener> myListeners = Lists.newArrayList();
   private String myName;
   private String myId;
-  
+
   @Override
   public String getID() {
     return myId == null ? myName : myId;
   }
-  
+
   @Override
   public String getName() {
     return myName;
   }
-  
+
   @Override
   public void setName(String name) {
     myName = name;
@@ -94,39 +97,47 @@ public Date findClosest(Date time, TimeUnit timeUnit, MoveDirection direction, D
   }
 
   public Date findClosest(Date time, TimeUnit timeUnit, MoveDirection direction, DayType dayType, Date limit) {
-    return doFindClosest(time, timeUnit, direction, dayType, limit);
+    return doFindClosest(time, timeUnit, direction, dayType, limit, MAX_WEEKEND_DAYS);
   }
-  
-  protected Date doFindClosest(Date time, DateFrameable framer, MoveDirection direction, DayType dayType, Date limit) {
+
+  protected Date doFindClosest(Date time, DateFrameable framer, MoveDirection direction, DayType findDayType, Date dateLimit, int maxWeekendDays) {
+    if (maxWeekendDays == 0) {
+      throw new UnsupportedOperationException("Error: all days are configured as 'weekend day'. That's not meaningful. Please, configure at least one day as non-weekend.");
+    }
     Date nextUnitStart = direction == GPCalendarCalc.MoveDirection.FORWARD ? framer.adjustRight(time)
         : framer.jumpLeft(time);
     int nextUnitMask = getDayMask(nextUnitStart);
-    switch (dayType) {
-    case WORKING:
-      if ((nextUnitMask & DayMask.WORKING) == DayMask.WORKING) {
-        return nextUnitStart;
-      }
-      break;
-    case WEEKEND:
-    case HOLIDAY:
-    case NON_WORKING:
-      if ((nextUnitMask & DayMask.WORKING) == 0) {
-        return nextUnitStart;
-      }
-      break;
-    default:
-      assert false : "Should not be here";
+    if ((nextUnitMask & DayMask.WEEKEND) == DayMask.WEEKEND) {
+      maxWeekendDays--;
+    } else {
+      maxWeekendDays = MAX_WEEKEND_DAYS;
     }
-    if (limit != null) {
-      if (direction == MoveDirection.FORWARD && nextUnitStart.compareTo(limit) >= 0
-          || direction == MoveDirection.BACKWARD && nextUnitStart.compareTo(limit) <= 0) {
+    switch (findDayType) {
+      case WORKING:
+        if ((nextUnitMask & DayMask.WORKING) == DayMask.WORKING) {
+          return nextUnitStart;
+        }
+        break;
+      case WEEKEND:
+      case HOLIDAY:
+      case NON_WORKING:
+        if ((nextUnitMask & DayMask.WORKING) == 0) {
+          return nextUnitStart;
+        }
+        break;
+      default:
+        assert false : "Should not be here";
+    }
+    if (dateLimit != null) {
+      if (direction == MoveDirection.FORWARD && nextUnitStart.compareTo(dateLimit) >= 0
+          || direction == MoveDirection.BACKWARD && nextUnitStart.compareTo(dateLimit) <= 0) {
         return null;
       }
     }
-    return doFindClosest(nextUnitStart, framer, direction, dayType, limit);
+    return doFindClosest(nextUnitStart, framer, direction, findDayType, dateLimit, maxWeekendDays);
   }
 
-  
+
   @Override
   public void addListener(GPCalendarListener listener) {
     myListeners.add(listener);
@@ -141,5 +152,6 @@ protected void fireCalendarChanged() {
       }
     }
   }
+
   public abstract int getDayMask(Date date);
 }
diff --git a/biz.ganttproject.core/src/biz/ganttproject/core/calendar/WeekendCalendarImpl.java b/biz.ganttproject.core/src/biz/ganttproject/core/calendar/WeekendCalendarImpl.java
index 6af703116e..2f41cf35f7 100644
--- a/biz.ganttproject.core/src/biz/ganttproject/core/calendar/WeekendCalendarImpl.java
+++ b/biz.ganttproject.core/src/biz/ganttproject/core/calendar/WeekendCalendarImpl.java
@@ -104,7 +104,7 @@ public List<GPCalendarActivity> getActivities(Date startDate, final Date endDate
     boolean isWeekendState = (getDayMask(curDayStart) & DayMask.WORKING) == 0;
     while (curDayStart.before(endDate)) {
       Date changeStateDayStart = doFindClosest(curDayStart, myFramer, MoveDirection.FORWARD,
-          isWeekendState ? DayType.WORKING : DayType.NON_WORKING, endDate);
+          isWeekendState ? DayType.WORKING : DayType.NON_WORKING, endDate, MAX_WEEKEND_DAYS);
       if (changeStateDayStart == null) {
         changeStateDayStart = endDate;
       }
@@ -214,7 +214,7 @@ public Date findClosestWorkingTime(Date time) {
     if ((dayMask & DayMask.WORKING) == DayMask.WORKING) {
       return time;
     }
-    return doFindClosest(time, myFramer, MoveDirection.FORWARD, DayType.WORKING, null);
+    return doFindClosest(time, myFramer, MoveDirection.FORWARD, DayType.WORKING, null, MAX_WEEKEND_DAYS);
   }
 
   private boolean isPublicHoliDay(Date curDayStart) {
diff --git a/ganttproject-tester/test/biz/ganttproject/core/calendar/WeekendCalendarImplTest.java b/ganttproject-tester/test/biz/ganttproject/core/calendar/WeekendCalendarImplTest.java
index 4a95d5da52..286d3c4bfa 100644
--- a/ganttproject-tester/test/biz/ganttproject/core/calendar/WeekendCalendarImplTest.java
+++ b/ganttproject-tester/test/biz/ganttproject/core/calendar/WeekendCalendarImplTest.java
@@ -23,20 +23,24 @@
 import java.util.List;
 import java.util.Locale;
 
-import biz.ganttproject.core.calendar.CalendarEvent.Type;
 import biz.ganttproject.core.calendar.GPCalendar.DayMask;
 import biz.ganttproject.core.calendar.GPCalendar.DayType;
 import biz.ganttproject.core.time.CalendarFactory;
 
+import biz.ganttproject.core.time.GanttCalendar;
 import com.google.common.base.Function;
 import com.google.common.collect.Collections2;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Lists;
 
 import junit.framework.TestCase;
+import org.junit.Assert;
+
+import static biz.ganttproject.core.calendar.GPCalendar.DayType.WEEKEND;
+import static java.util.Calendar.*;
 
 /**
- * Tests for {@link WeekendsCalendarImpl} class.
+ * Tests for {@link WeekendCalendarImpl} class.
  *
  * @author dbarashev (Dmitry Barashev)
  */
@@ -130,4 +134,29 @@ public void testOneOffWorkingWeekend() {
     assertEquals(0, calendar.getDayMask(CalendarFactory.createGanttCalendar(2014, 0, 11).getTime()) & DayMask.WORKING);
     assertEquals(DayMask.WEEKEND, calendar.getDayMask(CalendarFactory.createGanttCalendar(2014, 0, 11).getTime()) & DayMask.WEEKEND);
   }
+
+  /**
+   * @see <a href="https://github.com/bardsoftware/ganttproject/issues/1609>
+   *   Issue 1609: Weird failures if all days are weekend days
+   *   </a>
+   */
+  public void test_When_AllDaysAreWeekend_then_aUnsupportedOperationExceptionPreventsStackOverflow() {
+    WeekendCalendarImpl calendar = new WeekendCalendarImpl();
+    calendar.setWeekDayType(MONDAY, WEEKEND);
+    calendar.setWeekDayType(TUESDAY, WEEKEND);
+    calendar.setWeekDayType(WEDNESDAY, WEEKEND);
+    calendar.setWeekDayType(THURSDAY, WEEKEND);
+    calendar.setWeekDayType(FRIDAY, WEEKEND);
+    calendar.setWeekDayType(SATURDAY, WEEKEND);
+    calendar.setWeekDayType(SUNDAY, WEEKEND);
+    calendar.setPublicHolidays(TEST_EVENTS);
+
+    GanttCalendar helper = CalendarFactory.createGanttCalendar(2014, JANUARY, 0);
+    try {
+      calendar.findClosestWorkingTime(helper.getTime());
+      Assert.fail("Expected to get an UnsupportedOperationException");
+    } catch (UnsupportedOperationException exception) {
+      assertNotNull(exception.getMessage());
+    }
+  }
 }