diff --git a/Stdlib/Data/Bool/Base.juvix b/Stdlib/Data/Bool/Base.juvix
index ce31e40d..d266726d 100644
--- a/Stdlib/Data/Bool/Base.juvix
+++ b/Stdlib/Data/Bool/Base.juvix
@@ -36,3 +36,6 @@ or (a b : Bool) : Bool := a || b;
 
 --- Logical conjunction.
 and (a b : Bool) : Bool := a && b;
+
+builtin assert
+assert (x : Bool) : Bool := x;