diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -7,7 +7,6 @@
 
 #include "amount.h"
 #include "blockindex.h"
-#include "blockvalidity.h"
 #include "chain.h"
 #include "chainparams.h"
 #include "checkpoints.h"
diff --git a/src/txdb.h b/src/txdb.h
--- a/src/txdb.h
+++ b/src/txdb.h
@@ -7,7 +7,6 @@
 #define BITCOIN_TXDB_H
 
 #include "blockfileinfo.h"
-#include "blockindex.h"
 #include "coins.h"
 #include "dbwrapper.h"
 #include "diskblockpos.h"
diff --git a/src/validation.h b/src/validation.h
--- a/src/validation.h
+++ b/src/validation.h
@@ -12,6 +12,7 @@
 #endif
 
 #include "amount.h"
+#include "arith_uint256.h"
 #include "blockfileinfo.h"
 #include "chain.h"
 #include "coins.h"
diff --git a/src/versionbits.h b/src/versionbits.h
--- a/src/versionbits.h
+++ b/src/versionbits.h
@@ -5,10 +5,11 @@
 #ifndef BITCOIN_CONSENSUS_VERSIONBITS
 #define BITCOIN_CONSENSUS_VERSIONBITS
 
-#include "blockindex.h"
 #include "consensus/params.h"
 #include <map>
 
+class CBlockIndex;
+
 /** What block version to use for new blocks (pre versionbits) */
 static const int32_t VERSIONBITS_LAST_OLD_BLOCK_VERSION = 4;
 /** What bits to set in version for versionbits blocks */
diff --git a/src/versionbits.cpp b/src/versionbits.cpp
--- a/src/versionbits.cpp
+++ b/src/versionbits.cpp
@@ -4,6 +4,7 @@
 
 #include "versionbits.h"
 
+#include "blockindex.h"
 #include "consensus/params.h"
 
 const struct BIP9DeploymentInfo