diff --git a/sphinx/environment/adapters/toctree.py b/sphinx/environment/adapters/toctree.py
index 670ac786629..7d7e37612d6 100644
--- a/sphinx/environment/adapters/toctree.py
+++ b/sphinx/environment/adapters/toctree.py
@@ -216,7 +216,13 @@ def _resolve_toctree(
     for refnode in newnode.findall(nodes.reference):
         if url_re.match(refnode['refuri']) is None:
             rel_uri = builder.get_relative_uri(docname, refnode['refuri'])
-            refnode['refuri'] = rel_uri + refnode['anchorname']
+            if builder.name == 'singlehtml':
+                if len(refnode['anchorname']):
+                    refnode['refuri'] = refnode['anchorname']
+                else:
+                    refnode['refuri'] = rel_uri
+            else:
+                refnode['refuri'] = rel_uri + refnode['anchorname']
     return newnode