diff --git a/src/currency_core/tx_semantic_validation.cpp b/src/currency_core/tx_semantic_validation.cpp
index 57901f02f..9c2399dc5 100644
--- a/src/currency_core/tx_semantic_validation.cpp
+++ b/src/currency_core/tx_semantic_validation.cpp
@@ -23,6 +23,7 @@ namespace currency
   bool check_tx_inputs_keyimages_diff(const transaction& tx)
   {
     std::unordered_set<crypto::key_image> key_images;
+    std::unordered_set<crypto::hash> multisig_out_ids;
     crypto::key_image ki{};
     for(const auto& in_v : tx.vin)
     {
@@ -31,6 +32,12 @@ namespace currency
         if (!key_images.insert(ki).second)
           return false;
       }
+      else if (in_v.type() == typeid(txin_multisig))
+      {
+        const auto& ms_in = boost::get<txin_multisig>(in_v);
+        if (!multisig_out_ids.insert(ms_in.multisig_out_id).second)
+          return false;
+      }
     }
     return true;
   }