diff --git a/core/src/shapes.rs b/core/src/shapes.rs
index 8184f1d..0cedc7c 100644
--- a/core/src/shapes.rs
+++ b/core/src/shapes.rs
@@ -71,7 +71,7 @@ impl Shape {
 
     #[must_use]
     pub fn is_promotable(&self) -> bool {
-        Self::PROMOTABLE_SHAPES.contains(self)
+        matches!(self, Self::Knight | Self::Bishop | Self::Rook | Self::Queen)
     }
 
     #[must_use]