diff --git a/src/miner.h b/src/miner.h
--- a/src/miner.h
+++ b/src/miner.h
@@ -184,7 +184,7 @@
 
     // Methods for how to add transactions to a block.
     /** Add transactions based on tx "priority" */
-    void addPriorityTxs();
+    void addPriorityTxs() EXCLUSIVE_LOCKS_REQUIRED(mempool->cs);
     /**
      * Add transactions based on feerate including unconfirmed ancestors.
      * Increments nPackagesSelected / nDescendantsUpdated with corresponding
@@ -204,7 +204,8 @@
     /** Test if tx will still "fit" in the block */
     TestForBlockResult TestForBlock(CTxMemPool::txiter iter);
     /** Test if tx still has unconfirmed parents not yet in block */
-    bool isStillDependent(CTxMemPool::txiter iter);
+    bool isStillDependent(CTxMemPool::txiter iter)
+        EXCLUSIVE_LOCKS_REQUIRED(mempool->cs);
 
     // helper functions for addPackageTxs()
     /** Remove confirmed (inBlock) entries from given set */
diff --git a/src/test/mempool_tests.cpp b/src/test/mempool_tests.cpp
--- a/src/test/mempool_tests.cpp
+++ b/src/test/mempool_tests.cpp
@@ -20,6 +20,7 @@
 
 BOOST_AUTO_TEST_CASE(TestPackageAccounting) {
     CTxMemPool testPool;
+    LOCK(testPool.cs);
     TestMemPoolEntryHelper entry;
     CMutableTransaction parentOfAll;
 
@@ -229,6 +230,7 @@
     }
 
     CTxMemPool testPool;
+    LOCK(testPool.cs);
 
     // Nothing in pool, clear should do nothing:
     testPool.clear();