diff --git a/youtube_dl/jsinterp.py b/youtube_dl/jsinterp.py
index 95e6948ff..5731e264b 100644
--- a/youtube_dl/jsinterp.py
+++ b/youtube_dl/jsinterp.py
@@ -130,7 +130,7 @@ class JSInterpreter(object):
             return a % b
 
         m = re.match(
-            r'^(?P<func>[.a-zA-Z$]+)\((?P<args>[a-z0-9,]+)\)$', expr)
+            r'^(?P<func>[a-zA-Z$]+)\((?P<args>[a-z0-9,]+)\)$', expr)
         if m:
             fname = m.group('func')
             argvals = tuple([