diff --git a/lib/span.dart b/lib/span.dart
index 7ca0ca9..1d2152d 100644
--- a/lib/span.dart
+++ b/lib/span.dart
@@ -69,6 +69,8 @@
   bool operator ==(Span other) =>
     sourceUrl == other.sourceUrl && start == other.start && end == other.end;
 
+  int get hashCode => sourceUrl.hashCode + start + (31 * (end - start));
+
   String toString() => '<$runtimeType: $start $end $formatLocation $text>';
 }