diff --git a/src/bench/checkblock.cpp b/src/bench/checkblock.cpp
index 0fce7c518..d8c28a376 100644
--- a/src/bench/checkblock.cpp
+++ b/src/bench/checkblock.cpp
@@ -1,57 +1,57 @@
 // Copyright (c) 2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <bench/bench.h>
 
 #include <config.h>
 #include <consensus/validation.h>
 #include <streams.h>
 #include <validation.h>
 
 namespace block_bench {
 #include <bench/data/block413567.raw.h>
 }
 
 // These are the two major time-sinks which happen after we have fully received
 // a block off the wire, but before we can relay the block on to peers using
 // compact block relay.
 
 static void DeserializeBlockTest(benchmark::State &state) {
     CDataStream stream((const char *)block_bench::block413567,
                        (const char *)&block_bench::block413567[sizeof(
                            block_bench::block413567)],
                        SER_NETWORK, PROTOCOL_VERSION);
-    char a;
+    char a = '\0';
     stream.write(&a, 1); // Prevent compaction
 
     while (state.KeepRunning()) {
         CBlock block;
         stream >> block;
         assert(stream.Rewind(sizeof(block_bench::block413567)));
     }
 }
 
 static void DeserializeAndCheckBlockTest(benchmark::State &state) {
     CDataStream stream((const char *)block_bench::block413567,
                        (const char *)&block_bench::block413567[sizeof(
                            block_bench::block413567)],
                        SER_NETWORK, PROTOCOL_VERSION);
-    char a;
+    char a = '\0';
     stream.write(&a, 1); // Prevent compaction
 
     const Config &config = GetConfig();
     while (state.KeepRunning()) {
         // Note that CBlock caches its checked state, so we need to recreate it
         // here.
         CBlock block;
         stream >> block;
         assert(stream.Rewind(sizeof(block_bench::block413567)));
 
         CValidationState validationState;
         assert(CheckBlock(config, block, validationState));
     }
 }
 
 BENCHMARK(DeserializeBlockTest, 130);
 BENCHMARK(DeserializeAndCheckBlockTest, 160);