diff --git a/llvm/core.py b/llvm/core.py
index 20ad062..245ac65 100644
--- a/llvm/core.py
+++ b/llvm/core.py
@@ -379,6 +379,7 @@ class AttrEnum(Enum):
     ATTR_NAKED              = AttrVal.Naked
     ATTR_INLINE_HINT        = AttrVal.InlineHint
     ATTR_STACK_ALIGNMENT    = AttrVal.StackAlignment
+    ATTR_RETURNS_TWICE      = AttrVal.ReturnsTwice
 
 AttrEnum.declare()