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;
     }