pyderasn.py | 15 ++++++++-------

diff --git a/pyderasn.py b/pyderasn.py
index 887256bc9b1e697ecac32338d18a835672590488fabebf2d76cfe3c4329dc283..e5d3f2b0fe3c7e1545acbc72cd692f94d64171de5c01c9c32babc301495b1960 100755
--- a/pyderasn.py
+++ b/pyderasn.py
@@ -5816,13 +5816,14 @@                 )
             tail = v[EOC_LEN:]
             obj.lenindef = True
         obj._value = values
-        if not obj.ready:
-            raise DecodeError(
-                "not all values are ready",
-                klass=self.__class__,
-                decode_path=decode_path,
-                offset=offset,
-            )
+        for name, spec in iteritems(self.specs):
+            if name not in values and not spec.optional:
+                raise DecodeError(
+                    "%s value is not ready" % name,
+                    klass=self.__class__,
+                    decode_path=decode_path,
+                    offset=offset,
+                )
         obj.ber_encoded = ber_encoded
         return obj, tail