diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -983,7 +983,9 @@
     assert(!outputs.empty());
     ss << hash;
     ss << VARINT(outputs.begin()->second.GetHeight() * 2 +
-                 outputs.begin()->second.IsCoinBase());
+                         outputs.begin()->second.IsCoinBase()
+                     ? 1u
+                     : 0u);
     stats.nTransactions++;
     for (const auto &output : outputs) {
         ss << VARINT(output.first + 1);
diff --git a/src/undo.h b/src/undo.h
--- a/src/undo.h
+++ b/src/undo.h
@@ -33,8 +33,8 @@
     explicit TxInUndoSerializer(const Coin *pcoinIn) : pcoin(pcoinIn) {}
 
     template <typename Stream> void Serialize(Stream &s) const {
-        ::Serialize(
-            s, VARINT(pcoin->GetHeight() * 2 + (pcoin->IsCoinBase() ? 1 : 0)));
+        ::Serialize(s, VARINT(pcoin->GetHeight() * 2 +
+                              (pcoin->IsCoinBase() ? 1u : 0u)));
         if (pcoin->GetHeight() > 0) {
             // Required to maintain compatibility with older undo format.
             ::Serialize(s, uint8_t(0));