diff --git a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java
index 313a0d125..de8ced16b 100644
--- a/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java
+++ b/navalplanner-webapp/src/main/java/org/navalplanner/web/planner/TaskElementAdapter.java
@@ -328,8 +328,14 @@ public class TaskElementAdapter implements ITaskElementAdapter {
                 return Duration.ZERO;
             }
             Fraction fraction = fractionOfWorkingDayFor(effortDuration);
-            return new Duration(fraction.multiplyBy(
-                    Fraction.getFraction(DAY_MILLISECONDS, 1)).intValue());
+            try {
+                return new Duration(fraction.multiplyBy(
+                        Fraction.getFraction(DAY_MILLISECONDS, 1)).intValue());
+            } catch (ArithmeticException e) {
+                // if fraction overflows use floating point arithmetic
+                return new Duration(
+                        (int) (fraction.doubleValue() * DAY_MILLISECONDS));
+            }
         }
 
         @SuppressWarnings("unchecked")