diff --git a/Lib/json/decoder.py b/Lib/json/decoder.py
index 364e44d40cc307..803a7ff0e68e81 100644
--- a/Lib/json/decoder.py
+++ b/Lib/json/decoder.py
@@ -370,6 +370,8 @@ def raw_decode(self, s, idx=0):
         have extraneous data at the end.
 
         """
+        s = s.lstrip()
+
         try:
             obj, end = self.scan_once(s, idx)
         except StopIteration as err: