diff --git a/ChangeLog b/ChangeLog
index f5fdab097..e1747cb15 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2012-07-10  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
+
+	* SoObjects/SOGo/SOGoObject.m (-davBooleanForResult:): new method
+	that returns a valid DAV boolean from a BOOL.
+	(-isValidDAVBoolean:): new method that validates the value as a
+	DAV boolean.
+	(-resultForDAVBoolean:): new method that returns a BOOL from a DAV
+	boolean.
+
 2012-07-09  Ludovic Marcotte <lmarcotte@inverse.ca>
 
 	* Dropped old templates (SOGoAptMailDeletionReceipt.wox
diff --git a/SoObjects/Appointments/SOGoAppointmentFolder.m b/SoObjects/Appointments/SOGoAppointmentFolder.m
index 864d0ec26..6a79582d8 100644
--- a/SoObjects/Appointments/SOGoAppointmentFolder.m
+++ b/SoObjects/Appointments/SOGoAppointmentFolder.m
@@ -2250,28 +2250,18 @@ firstInstanceCalendarDateRange: (NGCalendarDateRange *) fir
 
 - (NSString *) davCalendarShowAlarms
 {
-  NSString *boolean;
-
-  if ([self showCalendarAlarms])
-    boolean = @"true";
-  else
-    boolean = @"false";
-
-  return boolean;
+  return [self davBooleanForResult: [self showCalendarAlarms]];
 }
 
 - (NSException *) setDavCalendarShowAlarms: (id) newBoolean
 {
   NSException *error;
 
-  error = nil;
-
-  if ([newBoolean isEqualToString: @"true"]
-      || [newBoolean isEqualToString: @"1"])
-    [self setShowCalendarAlarms: YES];
-  else if ([newBoolean isEqualToString: @"false"]
-           || [newBoolean isEqualToString: @"0"])
-    [self setShowCalendarAlarms: NO];
+  if ([self isValidDAVBoolean: newBoolean])
+    {
+      [self setShowCalendarAlarms: [self resultForDAVBoolean: newBoolean]];
+      error = nil;
+    }
   else
     error = [NSException exceptionWithHTTPStatus: 400
                                           reason: @"Bad boolean value."];
diff --git a/SoObjects/SOGo/SOGoObject.h b/SoObjects/SOGo/SOGoObject.h
index dc26fd78e..172f45a60 100644
--- a/SoObjects/SOGo/SOGoObject.h
+++ b/SoObjects/SOGo/SOGoObject.h
@@ -166,6 +166,10 @@
 		     parameters: (NSArray *) params;
 
 /* utilities */
+- (NSString *) davBooleanForResult: (BOOL) result;
+- (BOOL) isValidDAVBoolean: (NSString *) davBoolean;
+- (BOOL) resultForDAVBoolean: (NSString *) davBoolean;
+
 - (NSString *) labelForKey: (NSString *) key;
 
 /* description */
diff --git a/SoObjects/SOGo/SOGoObject.m b/SoObjects/SOGo/SOGoObject.m
index b7b42ba9f..8a0f0e24d 100644
--- a/SoObjects/SOGo/SOGoObject.m
+++ b/SoObjects/SOGo/SOGoObject.m
@@ -27,6 +27,7 @@
 #import <Foundation/NSClassDescription.h>
 #import <Foundation/NSFileManager.h>
 #import <Foundation/NSPathUtilities.h>
+#import <Foundation/NSSet.h>
 #import <Foundation/NSString.h>
 #import <Foundation/NSURL.h>
 #import <Foundation/NSValue.h>
@@ -1585,6 +1586,35 @@
   return exception;
 }
 
+- (NSString *) davBooleanForResult: (BOOL) result
+{
+  return (result ? @"true" : @"false");
+}
+
+- (BOOL) isValidDAVBoolean: (NSString *) davBoolean
+{
+  static NSSet *validBooleans = nil;
+
+  if (!validBooleans)
+    {
+      validBooleans = [NSSet setWithObjects: @"true", @"false", @"1", @"0",
+                             nil];
+      [validBooleans retain];
+    }
+
+  return [validBooleans containsObject: davBoolean];
+}
+
+- (BOOL) resultForDAVBoolean: (NSString *) davBoolean
+{
+  BOOL result;
+
+  result = ([davBoolean isEqualToString: @"true"]
+            || [davBoolean isEqualToString: @"1"]);
+
+  return result;
+}
+
 - (NSString *) labelForKey: (NSString *) key
 {
   return [self labelForKey: key inContext: context];