diff --git a/src/bin/TutorialD/Interpreter/RelationalExpr.hs b/src/bin/TutorialD/Interpreter/RelationalExpr.hs
index 7f9dffd5..b0b542b5 100644
--- a/src/bin/TutorialD/Interpreter/RelationalExpr.hs
+++ b/src/bin/TutorialD/Interpreter/RelationalExpr.hs
@@ -102,7 +102,11 @@ ungroupP = do
 extendP :: RelationalMarkerExpr a => Parser (RelationalExprBase a -> RelationalExprBase a)
 extendP = do
   reservedOp ":"
-  Extend <$> braces extendTupleExpressionP
+  extends <- braces (sepBy extendTupleExpressionP comma)
+  case extends of
+    [] -> pure (Restrict TruePredicate)
+    extends' ->
+      pure $ \expr -> foldl (\acc ext -> Extend ext acc) expr extends'
 
 semijoinP :: RelationalMarkerExpr a => Parser (RelationalExprBase a -> RelationalExprBase a -> RelationalExprBase a)
 semijoinP = do
diff --git a/test/TutorialD/Interpreter.hs b/test/TutorialD/Interpreter.hs
index fe9f997f..87ae6fa7 100644
--- a/test/TutorialD/Interpreter.hs
+++ b/test/TutorialD/Interpreter.hs
@@ -121,7 +121,8 @@ simpleRelTests = TestCase $ do
                       ("x:=relation{tuple{a 5}} : {b:=6}", mkRelationFromTuples simpleDAttributes [RelationTuple simpleDAttributes (V.fromList [IntegerAtom 5, IntegerAtom 6])]),
                       ("x:=relation{tuple{a 5}} : {b:=add(@a,5)}", mkRelationFromTuples simpleDAttributes [RelationTuple simpleDAttributes (V.fromList [IntegerAtom 5, IntegerAtom 10])]),
                       ("x:=relation{tuple{a 5}} : {b:=add(@a,\"spam\")}", Left (AtomFunctionTypeError "add" 2 IntegerAtomType TextAtomType)),
-                      ("x:=relation{tuple{a 5}} : {b:=add(add(@a,2),5)}", mkRelationFromTuples simpleDAttributes [RelationTuple simpleDAttributes (V.fromList [IntegerAtom 5, IntegerAtom 12])])
+                      ("x:=relation{tuple{a 5}} : {b:=add(add(@a,2),5)}", mkRelationFromTuples simpleDAttributes [RelationTuple simpleDAttributes (V.fromList [IntegerAtom 5, IntegerAtom 12])]),
+                      ("x:=false:{a:=1,b:=2}", mkRelationFromTuples simpleDAttributes [])
                      ]
     simpleAAttributes = A.attributesFromList [Attribute "a" IntegerAtomType]
     simpleBAttributes = A.attributesFromList [Attribute "d" IntegerAtomType]