diff --git a/src/validation.cpp b/src/validation.cpp
index 76b8401f1..3bff2d822 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3120,6 +3120,12 @@ static bool AcceptBlock(const std::shared_ptr<const CBlock>& pblock, CValidation
         if (pindex->nTx != 0) return true;  // This is a previously-processed block that was pruned
         if (!fHasMoreWork) return true;     // Don't process less-work chains
         if (fTooFarAhead) return true;      // Block height is too high
+
+        // Protect against DoS attacks from low-work chains.
+        // If our tip is behind, a peer could try to send us
+        // low-work blocks on a fake chain that we would never
+        // request; don't process these.
+        if (pindex->nChainWork < nMinimumChainWork) return true;
     }
     if (fNewBlock) *fNewBlock = true;