diff --git a/src/utils/vec_ext.rs b/src/utils/vec_ext.rs
index fc74ee3..a37a836 100644
--- a/src/utils/vec_ext.rs
+++ b/src/utils/vec_ext.rs
@@ -13,12 +13,12 @@ impl<T> VecExt<T> for [T] {
     fn get_mut_res(&mut self, index: usize) -> Result<&mut T> {
         let len = self.len();
         self.get_mut(index)
-            .ok_or(PkmnError::IndexOutOfBounds { index, len }.into())
+            .ok_or_else(|| PkmnError::IndexOutOfBounds { index, len }.into())
     }
 
     fn get_res(&self, index: usize) -> Result<&T> {
         self.get(index)
-            .ok_or(PkmnError::IndexOutOfBounds { index, len: self.len() }.into())
+            .ok_or_else(|| PkmnError::IndexOutOfBounds { index, len: self.len() }.into())
     }
 }
 
@@ -26,11 +26,11 @@ impl<T> VecExt<T> for Vec<T> {
     fn get_mut_res(&mut self, index: usize) -> Result<&mut T> {
         let len = self.len();
         self.get_mut(index)
-            .ok_or(PkmnError::IndexOutOfBounds { index, len }.into())
+            .ok_or_else(|| PkmnError::IndexOutOfBounds { index, len }.into())
     }
 
     fn get_res(&self, index: usize) -> Result<&T> {
         self.get(index)
-            .ok_or(PkmnError::IndexOutOfBounds { index, len: self.len() }.into())
+            .ok_or_else(|| PkmnError::IndexOutOfBounds { index, len: self.len() }.into())
     }
 }