diff --git a/lightning-invoice/src/lib.rs b/lightning-invoice/src/lib.rs
index df0412bfc5d..610f739e57a 100644
--- a/lightning-invoice/src/lib.rs
+++ b/lightning-invoice/src/lib.rs
@@ -550,7 +550,7 @@ impl InvoiceBuilder<tb::False, tb::False, tb::False, tb::False, tb::False, tb::F
 			amount: None,
 			si_prefix: None,
 			timestamp: None,
-			tagged_fields: Vec::new(),
+			tagged_fields: Vec::with_capacity(8),
 			error: None,
 
 			phantom_d: core::marker::PhantomData,