diff --git a/src/miner.cpp b/src/miner.cpp
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -549,7 +549,8 @@
     // Update nExtraNonce
     static uint256 hashPrevBlock;
     if (hashPrevBlock != pblock->hashPrevBlock) {
-        nExtraNonce = 0;
+        FastRandomContext rng;
+        nExtraNonce = rng.rand32();
         hashPrevBlock = pblock->hashPrevBlock;
     }
 
diff --git a/test/functional/rpc_blockchain.py b/test/functional/rpc_blockchain.py
--- a/test/functional/rpc_blockchain.py
+++ b/test/functional/rpc_blockchain.py
@@ -34,6 +34,7 @@
 from test_framework.p2p import P2PInterface
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
+    assert_approx,
     assert_equal,
     assert_greater_than,
     assert_greater_than_or_equal,
@@ -389,7 +390,7 @@
         assert_equal(blockinfo['height'], blockheaderinfo['height'])
         assert_equal(blockinfo['versionHex'], blockheaderinfo['versionHex'])
         assert_equal(blockinfo['version'], blockheaderinfo['version'])
-        assert_equal(blockinfo['size'], 181)
+        assert_approx(blockinfo['size'], 181)
         assert_equal(blockinfo['merkleroot'], blockheaderinfo['merkleroot'])
         # Verify transaction data by check the hex values
         for tx in blockinfo['tx']: