diff --git a/ext/fg/js/source.js b/ext/fg/js/source.js
index c9d70215..07006cc9 100644
--- a/ext/fg/js/source.js
+++ b/ext/fg/js/source.js
@@ -61,7 +61,7 @@ class TextSourceRange {
         const state = TextSourceRange.seekBackward(this.range.startContainer, this.range.startOffset, length);
         this.range.setStart(state.node, state.offset);
         this.rangeStartOffset = this.range.startOffset;
-        this.content = state.content;
+        this.content = state.content + this.content;
         return length - state.remainder;
     }