diff --git a/src/main.cpp b/src/main.cpp
index 0c9e43a9..fe35fbaf 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -368,6 +368,9 @@ bool CTransaction::IsStandard() const
     if (nVersion > CTransaction::CURRENT_VERSION)
         return false;
 
+    if (!IsFinal())
+        return false;
+
     BOOST_FOREACH(const CTxIn& txin, vin)
     {
         // Biggest 'standard' txin is a 3-signature 3-of-3 CHECKMULTISIG