diff --git a/src/avalanche/processor.cpp b/src/avalanche/processor.cpp
--- a/src/avalanche/processor.cpp
+++ b/src/avalanche/processor.cpp
@@ -287,6 +287,11 @@
 bool Processor::addBlockToReconcile(const CBlockIndex *pindex) {
     bool isAccepted;
 
+    if (!pindex) {
+        // IsWorthPolling expects this to be non-null, so bail early.
+        return false;
+    }
+
     {
         LOCK(cs_main);
         if (!IsWorthPolling(pindex)) {
@@ -314,6 +319,11 @@
 }
 
 bool Processor::isAccepted(const CBlockIndex *pindex) const {
+    if (!pindex) {
+        // CBlockIndexWorkComparator expects this to be non-null, so bail early.
+        return false;
+    }
+
     auto r = blockVoteRecords.getReadView();
     auto it = r->find(pindex);
     if (it == r.end()) {
@@ -334,6 +344,11 @@
 }
 
 int Processor::getConfidence(const CBlockIndex *pindex) const {
+    if (!pindex) {
+        // CBlockIndexWorkComparator expects this to be non-null, so bail early.
+        return -1;
+    }
+
     auto r = blockVoteRecords.getReadView();
     auto it = r->find(pindex);
     if (it == r.end()) {
diff --git a/src/avalanche/test/processor_tests.cpp b/src/avalanche/test/processor_tests.cpp
--- a/src/avalanche/test/processor_tests.cpp
+++ b/src/avalanche/test/processor_tests.cpp
@@ -455,6 +455,29 @@
     BOOST_CHECK(m_processor->isAccepted(pindex));
 }
 
+BOOST_AUTO_TEST_CASE(block_null) {
+    // Check that null case is handled on the public interface
+    BOOST_CHECK(!m_processor->isAccepted(nullptr));
+    BOOST_CHECK_EQUAL(m_processor->getConfidence(nullptr), -1);
+
+    BOOST_CHECK(!m_processor->addBlockToReconcile(nullptr));
+
+    // Check that adding blocks to vote on doesn't change the outcome. A
+    // comparator is used under the hood, and this is skipped if there are no
+    // vote records.
+    CBlock block = CreateAndProcessBlock({}, CScript());
+    const BlockHash blockHash = block.GetHash();
+    CBlockIndex *pindex;
+    {
+        LOCK(cs_main);
+        pindex = g_chainman.m_blockman.LookupBlockIndex(blockHash);
+    }
+    BOOST_CHECK(m_processor->addBlockToReconcile(pindex));
+
+    BOOST_CHECK(!m_processor->isAccepted(nullptr));
+    BOOST_CHECK_EQUAL(m_processor->getConfidence(nullptr), -1);
+}
+
 namespace {
 Response next(Response &r) {
     auto copy = r;