diff --git a/crates/oyster_parser/src/cst.rs b/crates/oyster_parser/src/cst.rs
index f2e045e..1a4cb96 100644
--- a/crates/oyster_parser/src/cst.rs
+++ b/crates/oyster_parser/src/cst.rs
@@ -29,7 +29,7 @@ impl<'a> From<&'a str> for ParseTree {
 }
 
 fn build_tree(parser: &mut Parser) -> Vec<ParseTree> {
-    let mut children = vec![];
+    let mut children = Vec::with_capacity(4);
 
     while let Some(ev) = parser.next() {
         match ev {