diff --git a/src/miner.cpp b/src/miner.cpp
index 6a3451084..1a22a1626 100644
--- a/src/miner.cpp
+++ b/src/miner.cpp
@@ -905,7 +905,7 @@ void static BitcoinMiner()
                 // (x_1, x_2, ...) = A(I, V, n, k)
                 LogPrint("pow", "Running Equihash solver \"%s\" with nNonce = %s\n",solver, pblock->nNonce.ToString());
                 arith_uint256 hashTarget = HASHTarget;
-                for (z=31; z>=0; z--)
+                int32_t z; for (z=31; z>=0; z--)
                     fprintf(stderr,"%02x",((uint8_t *)&hashTarget)[z]);
                 fprintf(stderr," running solver\n");
                 std::function<bool(std::vector<unsigned char>)> validBlock =