diff --git a/src/main.cpp b/src/main.cpp
index 1e0194e2cd..e8bc68fe64 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -2587,6 +2587,9 @@ bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW, bo
 {
     // These are checks that are independent of context.
 
+    if (block.fChecked)
+        return true;
+
     // Check that the header is valid (particularly PoW).  This is mostly
     // redundant with the call in AcceptBlockHeader.
     if (!CheckBlockHeader(block, state, fCheckPOW))
@@ -2642,6 +2645,9 @@ bool CheckBlock(const CBlock& block, CValidationState& state, bool fCheckPOW, bo
         return state.DoS(100, error("CheckBlock(): out-of-bounds SigOpCount"),
                          REJECT_INVALID, "bad-blk-sigops", true);
 
+    if (fCheckPOW && fCheckMerkleRoot)
+        block.fChecked = true;
+
     return true;
 }
 
diff --git a/src/primitives/block.h b/src/primitives/block.h
index 7fe8c84cb7..86106098f5 100644
--- a/src/primitives/block.h
+++ b/src/primitives/block.h
@@ -77,6 +77,9 @@ public:
     // network and disk
     std::vector<CTransaction> vtx;
 
+    // memory only
+    mutable bool fChecked;
+
     CBlock()
     {
         SetNull();
@@ -100,6 +103,7 @@ public:
     {
         CBlockHeader::SetNull();
         vtx.clear();
+        fChecked = false;
     }
 
     CBlockHeader GetBlockHeader() const