diff --git a/readthedocs/doc_builder/backends/mkdocs.py b/readthedocs/doc_builder/backends/mkdocs.py
index f97194b0f19..93b3030bb02 100644
--- a/readthedocs/doc_builder/backends/mkdocs.py
+++ b/readthedocs/doc_builder/backends/mkdocs.py
@@ -98,7 +98,7 @@ def append_conf(self, **kwargs):
         # Will be available in the JavaScript as READTHEDOCS_DATA.
         readthedocs_data = {
             'project': self.version.project.slug,
-            'version': self.version.verbose_name,
+            'version': self.version.slug,
             'language': self.version.project.language,
             'page': None,
             'theme': "readthedocs",