diff --git a/core/constant_inc.php b/core/constant_inc.php
index 5c56118feb..42cde6bb64 100644
--- a/core/constant_inc.php
+++ b/core/constant_inc.php
@@ -226,6 +226,11 @@
 define( 'BUG_UPDATE_TYPE_REOPEN', 'reopen' );
 define( 'BUG_UPDATE_TYPE_CHANGE_STATUS', 'change_status' );
 
+# confirmation message types
+define( 'CONFIRMATION_TYPE_SUCCESS', 0 );
+define( 'CONFIRMATION_TYPE_WARNING', 1 );
+define( 'CONFIRMATION_TYPE_FAILURE', 2 );
+
 # error messages
 define( 'ERROR_GENERIC', 0 );
 define( 'ERROR_SQL', 1 );
@@ -623,4 +628,4 @@
 
 # Maximum number of bugs that are treated simutaneously in export procedures,
 # to keep memory usage under control. Do not exceed 1000 if using Oracle DB.
-define( 'EXPORT_BLOCK_SIZE', 500 );
\ No newline at end of file
+define( 'EXPORT_BLOCK_SIZE', 500 );
diff --git a/core/html_api.php b/core/html_api.php
index d6422d97a8..889689cd5d 100644
--- a/core/html_api.php
+++ b/core/html_api.php
@@ -374,20 +374,21 @@ function html_top_banner() {
  *                               the buttons; if label is null or unspecified,
  *                               the default 'proceed' text will be displayed.
  * @param string $p_message      Message to display to the user.
- * @param string $p_type         One of 'success', 'warning', 'failure'
+ * @param string $p_type         One of the constants CONFIRMATION_TYPE_SUCCESS,
+ *                               CONFIRMATION_TYPE_WARNING, CONFIRMATION_TYPE_FAILURE
  * @return void
  */
-function html_operation_successful_buttons( array $p_buttons, $p_message = '', $p_type = 'success' ) {
+function html_operation_successful_buttons( array $p_buttons, $p_message = '', $p_type = CONFIRMATION_TYPE_SUCCESS ) {
 	switch( $p_type ) {
-		case 'failure':
+		case CONFIRMATION_TYPE_FAILURE:
 			$t_alert_css = 'alert-danger';
 			$t_message = lang_get( 'operation_failed' );
 			break;
-		case 'warning':
+		case CONFIRMATION_TYPE_WARNING:
 			$t_message = lang_get( 'operation_warnings' );
 			$t_alert_css = 'alert-warning';
 			break;
-		case 'success':
+		case CONFIRMATION_TYPE_SUCCESS:
 		default:
 			$t_alert_css = 'alert-success';
 			$t_message = lang_get( 'operation_successful' );
@@ -438,7 +439,7 @@ function html_operation_warning( $p_redirect_url, $p_message = '' ) {
 	html_operation_successful_buttons(
 		array( array( $p_redirect_url ) ),
 		$p_message,
-		'warning'
+		CONFIRMATION_TYPE_WARNING
 	);
 }
 
@@ -452,7 +453,7 @@ function html_operation_failure( $p_redirect_url, $p_message = '' ) {
 	html_operation_successful_buttons(
 		array( array( $p_redirect_url ) ),
 		$p_message,
-		'failure'
+		CONFIRMATION_TYPE_FAILURE
 	);
 }