diff --git a/dibi/dibi.php b/dibi/dibi.php
index 609fb650..aff38034 100644
--- a/dibi/dibi.php
+++ b/dibi/dibi.php
@@ -638,6 +638,9 @@ class dibi
 	 */
 	public static function addSubst($expr, $subst)
 	{
+		if ($expr === '') {
+			trigger_error(__METHOD__ . ': empty substitutions will probably be deprecated.', E_USER_NOTICE);
+		}
 		self::$substs[$expr] = $subst;
 	}
 
@@ -653,7 +656,7 @@ class dibi
 		if ($expr === TRUE) {
 			self::$substs = array();
 		} else {
-			unset(self::$substs[':'.$expr.':']);
+			unset(self::$substs[$expr]);
 		}
 	}
 
diff --git a/examples/substitutions.php b/examples/substitutions.php
index d50a2ff3..ebf0429b 100644
--- a/examples/substitutions.php
+++ b/examples/substitutions.php
@@ -23,16 +23,6 @@ dibi::test("UPDATE :blog:items SET [text]='Hello World'");
 
 
 
-// create new substitution :: (empty)  ==>  my_
-dibi::addSubst('', 'my_');
-
-dibi::test("UPDATE [database.::table] SET [text]='Hello World'");
-// -> UPDATE [database].[my_table] SET [text]='Hello World'
-
-
-
-
-
 // create substitution fallback
 function substFallBack($expr)
 {