diff --git a/src/collections/string_pool.rs b/src/collections/string_pool.rs
index 80ced6346d462aef57339049fc57f06395c1e473..ad281e630f0bba4c2d192f01f878509d7ae1b0cf 100644
--- a/src/collections/string_pool.rs
+++ b/src/collections/string_pool.rs
@@ -31,7 +31,7 @@ impl<'a> StringRef<'a> {
 
     /// `new_empty` creates a empty StringRef. It is a null pointer with a
     /// length of zero.
-    pub(crate) fn new_empty() -> StringRef<'static> {
+    pub(crate) const fn new_empty() -> StringRef<'static> {
         StringRef{ data: null(), length: 0, _phantom: PhantomData }
     }