diff --git a/CRM/Twingle/Profile.php b/CRM/Twingle/Profile.php
index 37e9365..0be09b9 100644
--- a/CRM/Twingle/Profile.php
+++ b/CRM/Twingle/Profile.php
@@ -145,6 +145,21 @@ class CRM_Twingle_Profile {
     $this->data[$attribute_name] = $value;
   }
 
+  /**
+   * Get the CiviCRM transaction ID (to be used in contributions and recurring contributions)
+   *
+   * @param $twingle_id string Twingle ID
+   * @return string CiviCRM transaction ID
+   */
+  public function getTransactionID($twingle_id) {
+    $prefix = CRM_Core_BAO_Setting::getItem('de.systopia.twingle', 'twingle_prefix');
+    if (empty($prefix)) {
+      return $twingle_id;
+    } else {
+      return $prefix . $twingle_id;
+    }
+  }
+
   /**
    * Verifies whether the profile is valid (i.e. consistent and not colliding
    * with other profiles).
diff --git a/api/v3/TwingleDonation/Cancel.php b/api/v3/TwingleDonation/Cancel.php
index 7a8c5fc..00fc6a8 100644
--- a/api/v3/TwingleDonation/Cancel.php
+++ b/api/v3/TwingleDonation/Cancel.php
@@ -80,15 +80,16 @@ function civicrm_api3_twingle_donation_Cancel($params) {
     }
 
     // Retrieve (recurring) contribution.
+    $default_profile = CRM_Twingle_Profile::getProfile('default');
     try {
       $contribution = civicrm_api3('Contribution', 'getsingle', array(
-        'trxn_id' => $params['trx_id'],
+        'trxn_id' => $default_profile->getTransactionID($params['trx_id']),
       ));
       $contribution_type = 'Contribution';
     }
     catch (CiviCRM_API3_Exception $exception) {
       $contribution = civicrm_api3('ContributionRecur', 'getsingle', array(
-        'trxn_id' => $params['trx_id'],
+          'trxn_id' => $default_profile->getTransactionID($params['trx_id']),
       ));
       $contribution_type = 'ContributionRecur';
     }
diff --git a/api/v3/TwingleDonation/Endrecurring.php b/api/v3/TwingleDonation/Endrecurring.php
index 83f20e0..baecb32 100644
--- a/api/v3/TwingleDonation/Endrecurring.php
+++ b/api/v3/TwingleDonation/Endrecurring.php
@@ -72,8 +72,9 @@ function civicrm_api3_twingle_donation_endrecurring($params) {
       );
     }
 
+    $default_profile = CRM_Twingle_Profile::getProfile('default');
     $contribution = civicrm_api3('ContributionRecur', 'getsingle', array(
-      'trxn_id' => $params['trx_id'],
+      'trxn_id' => $default_profile->getTransactionID($params['trx_id']),
     ));
     // End SEPA mandate (which ends the associated recurring contribution) or
     // recurring contributions.
diff --git a/api/v3/TwingleDonation/Submit.php b/api/v3/TwingleDonation/Submit.php
index 9a52c42..2bc3d3a 100644
--- a/api/v3/TwingleDonation/Submit.php
+++ b/api/v3/TwingleDonation/Submit.php
@@ -278,10 +278,10 @@ function civicrm_api3_twingle_donation_Submit($params) {
     // Do not process an already existing contribution with the given
     // transaction ID.
     $existing_contribution = civicrm_api3('Contribution', 'get', array(
-      'trxn_id' => $params['trx_id']
+      'trxn_id' => $profile->getTransactionID($params['trx_id'])
     ));
     $existing_contribution_recur = civicrm_api3('ContributionRecur', 'get', array(
-      'trxn_id' => $params['trx_id']
+      'trxn_id' => $profile->getTransactionID($params['trx_id'])
     ));
     if ($existing_contribution['count'] > 0 || $existing_contribution_recur['count'] > 0) {
       throw new CiviCRM_API3_Exception(
@@ -511,7 +511,7 @@ function civicrm_api3_twingle_donation_Submit($params) {
     $contribution_data = array(
       'contact_id' => (isset($organisation_id) ? $organisation_id : $contact_id),
       'currency' => $params['currency'],
-      'trxn_id' => $params['trx_id'],
+      'trxn_id' => $profile->getTransactionID($params['trx_id']),
       'payment_instrument_id' => $params['payment_instrument_id'],
       'amount' => $params['amount'] / 100,
       'total_amount' => $params['amount'] / 100,
diff --git a/settings/twingle.setting.php b/settings/twingle.setting.php
index 164c97e..1df4d27 100644
--- a/settings/twingle.setting.php
+++ b/settings/twingle.setting.php
@@ -31,4 +31,18 @@ return array(
     'is_contact' => 0,
     'description' => 'Whether to provide CiviSEPA functionality for manual debit payment method. This requires the CiviSEPA (org.project60.sepa) extension be installed.',
   ),
+  'twingle_prefix' => array(
+      'group_name' => 'de.systopia.twingle',
+      'group' => 'de.systopia.twingle',
+      'name' => 'twingle_prefix',
+      'type' => CRM_Utils_Type::T_STRING,
+      'quick_form_type' => 'Element',
+      'html_type' => 'text',
+      'title' => 'Twingle ID Prefix',
+      'default' => '',
+      'add' => '4.6',
+      'is_domain' => 1,
+      'is_contact' => 0,
+      'description' => 'You can use this setting to add a prefix to the Twingle transaction ID, in order to avoid collisions with other transaction ids.',
+  ),
 );
diff --git a/templates/CRM/Twingle/Form/Settings.hlp b/templates/CRM/Twingle/Form/Settings.hlp
index 2f0a45a..b9ff9d1 100644
--- a/templates/CRM/Twingle/Form/Settings.hlp
+++ b/templates/CRM/Twingle/Form/Settings.hlp
@@ -15,3 +15,7 @@
 {htxt id='id-twingle_use_sepa'}
     {ts domain="de.systopia.twingle" 1="<a href=\"https://github.com/project60/org.project60.sepa\" target=\"_blank\">CiviSEPA (<kbd>org.project60.sepa</kbd>) extension</a>"}When the %1 is enabled and one of its payment instruments is assigned to a Twingle payment method (practically the <em>debit_manual</em> payment method), submitting a Twingle donation through the API will create a SEPA mandate with the given data.{/ts}
 {/htxt}
+
+{htxt id='id-twingle_prefix'}
+    {ts domain="de.systopia.twingle"}You can use this setting to add a prefix to the Twingle transaction ID, in order to avoid collisions with other transaction ids.{/ts}
+{/htxt}