diff --git a/src/pyj/read_book/db.pyj b/src/pyj/read_book/db.pyj
index e0b39daa2d..dc4d3b0059 100644
--- a/src/pyj/read_book/db.pyj
+++ b/src/pyj/read_book/db.pyj
@@ -155,6 +155,9 @@ class DB:
         req.onerror = def(event):
             proceed(_('Failed to store book data ({0}) with error: {1}').format(name, get_error_details(event)))
 
+    def clear_mathjax(self, proceed):
+        self.idb.transaction(['mathjax'], 'readwrite').objectStore('mathjax').clear().onsuccess = proceed
+
     def store_mathjax_file(self, name, xhr, proceed):
         data = xhr.response
         if not self.supports_blobs:
diff --git a/src/pyj/read_book/ui.pyj b/src/pyj/read_book/ui.pyj
index 8d8ec5f3a9..b21b26f12a 100644
--- a/src/pyj/read_book/ui.pyj
+++ b/src/pyj/read_book/ui.pyj
@@ -261,7 +261,9 @@ class ReadUI:
             if mathjax_info.version is MATHJAX_VERSION:
                 return proceed()
             print('Upgrading MathJax, previous version:', mathjax_info.version)
-            self.get_mathjax_manifest(mathjax_info, proceed)
+            self.db.clear_mathjax(def():
+                self.get_mathjax_manifest(mathjax_info, proceed)
+            )
         )
 
     def get_mathjax_manifest(self, mathjax_info, proceed):