diff --git a/src/source.rs b/src/source.rs
index 48b2ea3..b7ada7d 100644
--- a/src/source.rs
+++ b/src/source.rs
@@ -1,5 +1,5 @@
 use std::{
-  any::Any,
+  any::{Any, TypeId},
   borrow::Cow,
   convert::{TryFrom, TryInto},
   fmt,
@@ -110,6 +110,7 @@ impl<T: Any> AsAny for T {
 
 pub trait DynEq {
   fn dyn_eq(&self, other: &dyn Any) -> bool;
+  fn type_id(&self) -> TypeId;
 }
 
 impl<E: Eq + Any> DynEq for E {
@@ -120,10 +121,17 @@ impl<E: Eq + Any> DynEq for E {
       false
     }
   }
+
+  fn type_id(&self) -> TypeId {
+    TypeId::of::<E>()
+  }
 }
 
 impl PartialEq for dyn Source {
   fn eq(&self, other: &Self) -> bool {
+    if self.as_any().type_id() != other.as_any().type_id() {
+      return false;
+    }
     self.dyn_eq(other.as_any())
   }
 }
diff --git a/src/with_indices.rs b/src/with_indices.rs
index f199e5b..103b46e 100644
--- a/src/with_indices.rs
+++ b/src/with_indices.rs
@@ -5,7 +5,7 @@ pub struct WithIndices<T: AsRef<str>> {
   /// line is a string reference
   pub line: T,
   /// the byte position of each `char` in `line` string slice .
-  pub indices_indexes: OnceCell<Box<[u32]>>,
+  pub indices_indexes: OnceCell<Vec<usize>>,
 }
 
 impl<T: AsRef<str>> WithIndices<T> {
@@ -23,24 +23,19 @@ impl<T: AsRef<str>> WithIndices<T> {
       return "";
     }
 
-    let indices_indexes = self.indices_indexes.get_or_init(|| {
-      self
-        .line
-        .as_ref()
-        .char_indices()
-        .map(|(i, _)| i as u32)
-        .collect::<Vec<_>>()
-        .into_boxed_slice()
-    });
+    let line = self.line.as_ref();
+    let indices_indexes = self
+      .indices_indexes
+      .get_or_init(|| line.char_indices().map(|(i, _)| i).collect::<Vec<_>>());
 
-    let str_len = self.line.as_ref().len() as u32;
-    let start = *indices_indexes.get(start_index).unwrap_or(&str_len) as usize;
-    let end = *indices_indexes.get(end_index).unwrap_or(&str_len) as usize;
+    let str_len = line.len();
+    let start = *indices_indexes.get(start_index).unwrap_or(&str_len);
+    let end = *indices_indexes.get(end_index).unwrap_or(&str_len);
     unsafe {
       // SAFETY: Since `indices` iterates over the `CharIndices` of `self`, we can guarantee
       // that the indices obtained from it will always be within the bounds of `self` and they
       // will always lie on UTF-8 sequence boundaries.
-      self.line.as_ref().get_unchecked(start..end)
+      line.get_unchecked(start..end)
     }
   }
 }