diff --git a/youtube_dl/jsinterp.py b/youtube_dl/jsinterp.py
index c40cd376d1..b4617fbad0 100644
--- a/youtube_dl/jsinterp.py
+++ b/youtube_dl/jsinterp.py
@@ -61,7 +61,7 @@ def interpret_expression(self, expr, local_vars, allow_recursion):
             pass
 
         m = re.match(
-            r'^(?P<var>[a-zA-Z0-9_]+)\.(?P<member>[^(]+)(?:\(+(?P<args>[^()]*)\))?$',
+            r'^(?P<var>[$a-zA-Z0-9_]+)\.(?P<member>[^(]+)(?:\(+(?P<args>[^()]*)\))?$',
             expr)
         if m:
             variable = m.group('var')