month goes from 0 - 11
diff --git a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/DateTime.java b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/DateTime.java
index 975371d..c96410f 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/DateTime.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/DateTime.java
@@ -262,9 +262,9 @@
 	checkWidget ();
 	if ((style & SWT.CALENDAR) != 0) {
 		getDate();
-		return month + 1;
+		return month;
 	} else {
-		return calendar.get(Calendar.MONTH) + 1;
+		return calendar.get(Calendar.MONTH);
 	}
 }
 
@@ -636,7 +636,6 @@
 
 public void setMonth (int month) {
 	checkWidget ();
-	month--;
 	if (!isValid(Calendar.MONTH, month)) return;
 	if ((style & SWT.CALENDAR) != 0) {
 		this.month = month;