diff --git a/dibi/dibi.php b/dibi/dibi.php
index 44d45ccb..c4ba2f7f 100644
--- a/dibi/dibi.php
+++ b/dibi/dibi.php
@@ -683,7 +683,7 @@ class dibi
 	 */
 	public static function defaultSubstFallback($expr)
 	{
-		throw new InvalidStateException("Missing substitution for '$expr' expression.");
+		return ":$expr:";
 	}