diff --git a/src/astring.js b/src/astring.js
index 974b2ab9..12833fc0 100644
--- a/src/astring.js
+++ b/src/astring.js
@@ -1161,6 +1161,7 @@ class State {
         const { mapping } = this
         mapping.original = node.loc.start
         mapping.name = node.name
+        mapping.source = node.loc.source || mapping.source
         this.sourceMap.addMapping(mapping)
       }
       if (