diff --git a/src/libproc_macro/lib.rs b/src/libproc_macro/lib.rs
index f2936f2bca83d1cca1b8fd2da575b3ab0c797c18..4300c97d0ff662ca0fb8ebb4d74af760b09ee744 100644
--- a/src/libproc_macro/lib.rs
+++ b/src/libproc_macro/lib.rs
@@ -247,7 +247,7 @@ pub fn end(&self) -> LineColumn {
     #[unstable(feature = "proc_macro", issue = "38356")]
     pub fn join(&self, other: Span) -> Option<Span> {
         let self_loc = __internal::lookup_char_pos(self.0.lo());
-        let other_loc = __internal::lookup_char_pos(self.0.lo());
+        let other_loc = __internal::lookup_char_pos(other.0.lo());
 
         if self_loc.file.name != other_loc.file.name { return None }