diff --git a/lib/vector-vrl/functions/src/set_semantic_meaning.rs b/lib/vector-vrl/functions/src/set_semantic_meaning.rs
index f1b53065d96ed..f3095ecf12c46 100644
--- a/lib/vector-vrl/functions/src/set_semantic_meaning.rs
+++ b/lib/vector-vrl/functions/src/set_semantic_meaning.rs
@@ -163,6 +163,6 @@ impl FunctionExpression for SetSemanticMeaningFn {
     }
 
     fn type_def(&self, _: &TypeState) -> TypeDef {
-        TypeDef::null().infallible()
+        TypeDef::null().infallible().impure()
     }
 }