diff --git a/compiler/rustc_expand/src/proc_macro_server.rs b/compiler/rustc_expand/src/proc_macro_server.rs
index 71dfd3158dcc..eb5a78d271f9 100644
--- a/compiler/rustc_expand/src/proc_macro_server.rs
+++ b/compiler/rustc_expand/src/proc_macro_server.rs
@@ -635,7 +635,15 @@ impl server::Span for Rustc<'_, '_> {
     }
 
     fn byte_range(&mut self, span: Self::Span) -> Range<usize> {
-        Range { start: span.lo().0 as usize, end: span.hi().0 as usize }
+        let source_map = self.sess().source_map();
+
+        let relative_start_pos = source_map.lookup_byte_offset(span.lo()).pos;
+        let relative_end_pos = source_map.lookup_byte_offset(span.hi()).pos;
+
+        Range {
+            start: relative_start_pos.0 as usize,
+            end: relative_end_pos.0 as usize
+        }
     }
 
     fn start(&mut self, span: Self::Span) -> LineColumn {