diff --git a/ChangeLog b/ChangeLog
index a3950b176..36869115b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,8 @@
 2012-08-13  Wolfgang Sourdeau  <wsourdeau@inverse.ca>
 
+	* SoObjects/SOGo/NSString+Utilities.m
+	(-stringByReplacingPrefix:withPrefix:): new self-explicit method.
+
 	* OpenChange/SOGoMAPIDBFolder.m
 	(-childKeysOfType:includeDeleted:matchingQualifier:andSortOrderings:):
 	records now have a c_parent_path column in order to avoid fetch
diff --git a/SoObjects/SOGo/NSString+Utilities.h b/SoObjects/SOGo/NSString+Utilities.h
index 409c3fe86..df82535e2 100644
--- a/SoObjects/SOGo/NSString+Utilities.h
+++ b/SoObjects/SOGo/NSString+Utilities.h
@@ -74,7 +74,8 @@
 
 /* substrings */
 - (NSUInteger) countOccurrencesOfString: (NSString *) substring;
-
+- (NSString *) stringByReplacingPrefix: (NSString *) oldPrefix
+                            withPrefix: (NSString *) newPrefix;
 
 /* Those methods provide symmetric enc-/decryption via a XOR operation */
 - (NSString *) encryptWithKey: (NSString *) theKey;
diff --git a/SoObjects/SOGo/NSString+Utilities.m b/SoObjects/SOGo/NSString+Utilities.m
index ec04b9795..da5a69993 100644
--- a/SoObjects/SOGo/NSString+Utilities.m
+++ b/SoObjects/SOGo/NSString+Utilities.m
@@ -560,6 +560,24 @@ static int cssEscapingCount;
   return count;
 }
 
+- (NSString *) stringByReplacingPrefix: (NSString *) oldPrefix
+                            withPrefix: (NSString *) newPrefix
+{
+  NSUInteger oldPrefixLength;
+  NSString *newString;
+
+  if (![self hasPrefix: oldPrefix])
+    [NSException raise: NSInvalidArgumentException
+                 format: @"string does not have the specified prefix"];
+
+  oldPrefixLength = [oldPrefix length];
+  newString = [NSString stringWithFormat: @"%@%@",
+                        newPrefix,
+                        [self substringFromIndex: oldPrefixLength]];
+  
+  return newString;
+}
+
 - (NSString *) encryptWithKey: (NSString *) theKey
 {
   NSMutableData *encryptedPassword;