diff --git a/src/calibre/debug.py b/src/calibre/debug.py
index 873307505a..58385f9dc6 100644
--- a/src/calibre/debug.py
+++ b/src/calibre/debug.py
@@ -102,7 +102,7 @@ def main(args=sys.argv):
         main(['calibre'])
     elif opts.viewer:
         from calibre.gui2.viewer.main import main
-        vargs = ['ebook-viewer']
+        vargs = ['ebook-viewer', '--debug-javascript']
         if len(args) > 1:
             vargs.append(args[-1])
         main(vargs)
diff --git a/src/calibre/manual/develop.rst b/src/calibre/manual/develop.rst
index 5f359ad713..67c0c13db8 100644
--- a/src/calibre/manual/develop.rst
+++ b/src/calibre/manual/develop.rst
@@ -204,6 +204,10 @@ terminal. For example, you can start the GUI from the terminal as::
 
     calibre-debug -g
 
+Similarly, you can start the ebook-viewer as::
+
+    calibre-debug -w /path/to/file/to/be/viewed
+
 Executing arbitrary scripts in the calibre python environment
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^