diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -1269,9 +1269,12 @@
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     ;
     Amount GetCredit(const CTxOut &txout, const isminefilter &filter) const;
-    bool IsChange(const CTxOut &txout) const;
-    bool IsChange(const CScript &script) const;
-    Amount GetChange(const CTxOut &txout) const;
+    bool IsChange(const CTxOut &txout) const
+        EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    bool IsChange(const CScript &script) const
+        EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
+    Amount GetChange(const CTxOut &txout) const
+        EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     bool IsMine(const CTransaction &tx) const
         EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
     /** should probably be renamed to IsRelevantToMe */
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1390,7 +1390,7 @@
     // outputs are 'the send' and which are 'the change' will need to be
     // implemented (maybe extend CWalletTx to remember which output, if any, was
     // change).
-    LOCK(cs_wallet);
+    AssertLockHeld(cs_wallet);
     if (IsMine(script)) {
         CTxDestination address;
         if (!ExtractDestination(script, address)) {
@@ -1405,6 +1405,7 @@
 }
 
 Amount CWallet::GetChange(const CTxOut &txout) const {
+    AssertLockHeld(cs_wallet);
     if (!MoneyRange(txout.nValue)) {
         throw std::runtime_error(std::string(__func__) +
                                  ": value out of range");
@@ -1483,6 +1484,7 @@
 }
 
 Amount CWallet::GetChange(const CTransaction &tx) const {
+    LOCK(cs_wallet);
     Amount nChange = Amount::zero();
     for (const CTxOut &txout : tx.vout) {
         nChange += GetChange(txout);