diff --git a/compiler/crates/relay-config/src/typegen_config.rs b/compiler/crates/relay-config/src/typegen_config.rs
index ce13727f280e8..d5c9e79627336 100644
--- a/compiler/crates/relay-config/src/typegen_config.rs
+++ b/compiler/crates/relay-config/src/typegen_config.rs
@@ -137,6 +137,7 @@ impl Default for TypegenConfig {
             no_future_proof_enums: Default::default(),
             eager_es_modules: Default::default(),
             typescript_exclude_undefined_from_nullable_union: Default::default(),
+            experimental_emit_semantic_nullability_types: Default::default(),
         }
     }
 }