diff --git a/rust/macros/src/lib.rs b/rust/macros/src/lib.rs
index 135c24d..f117487 100644
--- a/rust/macros/src/lib.rs
+++ b/rust/macros/src/lib.rs
@@ -4,8 +4,7 @@ macro_rules! hashmap {
     (@count $($expr:expr),*) => (<[()]>::len(&[$(hashmap!(@discard $expr)),*]));
     ($($($key:expr => $expr:expr),+ $(,)?)?) => {{
         let cap = hashmap!(@count $($($key),*)?);
-        let mut map = ::std::collections::HashMap::new();
-        map.reserve(cap);
+        let mut map = ::std::collections::HashMap::with_capacity(cap);
         $($(map.insert($key, $expr);)*)?
         map
     }};