diff --git a/arcanist/linter/LocaleDependenceLinter.php b/arcanist/linter/LocaleDependenceLinter.php
--- a/arcanist/linter/LocaleDependenceLinter.php
+++ b/arcanist/linter/LocaleDependenceLinter.php
@@ -64,7 +64,7 @@
     "fgetwc",
     "fgetws",
     "fold_case",   // boost::locale::fold_case
-    //"fprintf"      // (via vfprintf)
+    "fprintf",     // (via vfprintf)
     "fputwc",
     "fputws",
     "fscanf",      // (via __vfscanf)
@@ -111,7 +111,7 @@
     "mbtowc",      // LC_CTYPE
     "mktime",
     "normalize",   // boost::locale::normalize
-    //"printf"       // LC_NUMERIC
+    "printf",      // LC_NUMERIC
     "putwc",
     "putwchar",
     "scanf",       // LC_NUMERIC
diff --git a/src/bench/bench_bitcoin.cpp b/src/bench/bench_bitcoin.cpp
--- a/src/bench/bench_bitcoin.cpp
+++ b/src/bench/bench_bitcoin.cpp
@@ -70,8 +70,8 @@
     SetupBenchArgs();
     std::string error;
     if (!gArgs.ParseParameters(argc, argv, error)) {
-        fprintf(stderr, "Error parsing command line arguments: %s\n",
-                error.c_str());
+        tfm::format(std::cerr, "Error parsing command line arguments: %s\n",
+                    error.c_str());
         return EXIT_FAILURE;
     }
 
@@ -87,8 +87,8 @@
 
     double scaling_factor;
     if (!ParseDouble(scaling_str, &scaling_factor)) {
-        fprintf(stderr, "Error parsing scaling factor as double: %s\n",
-                scaling_str.c_str());
+        tfm::format(std::cerr, "Error parsing scaling factor as double: %s\n",
+                    scaling_str.c_str());
         return EXIT_FAILURE;
     }
 
diff --git a/src/bitcoin-cli.cpp b/src/bitcoin-cli.cpp
--- a/src/bitcoin-cli.cpp
+++ b/src/bitcoin-cli.cpp
@@ -153,8 +153,8 @@
     SetupCliArgs();
     std::string error;
     if (!gArgs.ParseParameters(argc, argv, error)) {
-        fprintf(stderr, "Error parsing command line arguments: %s\n",
-                error.c_str());
+        tfm::format(std::cerr, "Error parsing command line arguments: %s\n",
+                    error.c_str());
         return EXIT_FAILURE;
     }
     if (argc < 2 || HelpRequested(gArgs) || gArgs.IsArgSet("-version")) {
@@ -175,22 +175,22 @@
             strUsage += "\n" + gArgs.GetHelpMessage();
         }
 
-        fprintf(stdout, "%s", strUsage.c_str());
+        tfm::format(std::cout, "%s", strUsage.c_str());
         if (argc < 2) {
-            fprintf(stderr, "Error: too few parameters\n");
+            tfm::format(std::cerr, "Error: too few parameters\n");
             return EXIT_FAILURE;
         }
         return EXIT_SUCCESS;
     }
     if (!fs::is_directory(GetDataDir(false))) {
-        fprintf(stderr,
-                "Error: Specified data directory \"%s\" does not exist.\n",
-                gArgs.GetArg("-datadir", "").c_str());
+        tfm::format(std::cerr,
+                    "Error: Specified data directory \"%s\" does not exist.\n",
+                    gArgs.GetArg("-datadir", "").c_str());
         return EXIT_FAILURE;
     }
     if (!gArgs.ReadConfigFiles(error, true)) {
-        fprintf(stderr, "Error reading configuration file: %s\n",
-                error.c_str());
+        tfm::format(std::cerr, "Error reading configuration file: %s\n",
+                    error.c_str());
         return EXIT_FAILURE;
     }
     // Check for -testnet or -regtest parameter (BaseParams() calls are only
@@ -198,7 +198,7 @@
     try {
         SelectBaseParams(gArgs.GetChainName());
     } catch (const std::exception &e) {
-        fprintf(stderr, "Error: %s\n", e.what());
+        tfm::format(std::cerr, "Error: %s\n", e.what());
         return EXIT_FAILURE;
     }
     return CONTINUE_EXECUTION;
@@ -615,7 +615,8 @@
     }
 
     if (strPrint != "") {
-        fprintf((nRet == 0 ? stdout : stderr), "%s\n", strPrint.c_str());
+        tfm::format(nRet == 0 ? std::cout : std::cerr, "%s\n",
+                    strPrint.c_str());
     }
     return nRet;
 }
@@ -627,7 +628,7 @@
 #endif
     SetupEnvironment();
     if (!SetupNetworking()) {
-        fprintf(stderr, "Error: Initializing networking failed\n");
+        tfm::format(std::cerr, "Error: Initializing networking failed\n");
         return EXIT_FAILURE;
     }
     event_set_log_callback(&libevent_log_cb);
diff --git a/src/bitcoin-tx.cpp b/src/bitcoin-tx.cpp
--- a/src/bitcoin-tx.cpp
+++ b/src/bitcoin-tx.cpp
@@ -109,8 +109,8 @@
     SetupBitcoinTxArgs();
     std::string error;
     if (!gArgs.ParseParameters(argc, argv, error)) {
-        fprintf(stderr, "Error parsing command line arguments: %s\n",
-                error.c_str());
+        tfm::format(std::cerr, "Error parsing command line arguments: %s\n",
+                    error.c_str());
         return EXIT_FAILURE;
     }
 
@@ -119,7 +119,7 @@
     try {
         SelectParams(gArgs.GetChainName());
     } catch (const std::exception &e) {
-        fprintf(stderr, "Error: %s\n", e.what());
+        tfm::format(std::cerr, "Error: %s\n", e.what());
         return EXIT_FAILURE;
     }
 
@@ -136,10 +136,10 @@
             "hex-encoded bitcoin transaction\n" +
             "\n";
         strUsage += gArgs.GetHelpMessage();
-        fprintf(stdout, "%s", strUsage.c_str());
+        tfm::format(std::cout, "%s", strUsage.c_str());
 
         if (argc < 2) {
-            fprintf(stderr, "Error: too few parameters\n");
+            tfm::format(std::cerr, "Error: too few parameters\n");
             return EXIT_FAILURE;
         }
 
@@ -763,20 +763,20 @@
     TxToUniv(tx, uint256(), entry);
 
     std::string jsonOutput = entry.write(4);
-    fprintf(stdout, "%s\n", jsonOutput.c_str());
+    tfm::format(std::cout, "%s\n", jsonOutput.c_str());
 }
 
 static void OutputTxHash(const CTransaction &tx) {
     // the hex-encoded transaction id.
     std::string strHexHash = tx.GetId().GetHex();
 
-    fprintf(stdout, "%s\n", strHexHash.c_str());
+    tfm::format(std::cout, "%s\n", strHexHash.c_str());
 }
 
 static void OutputTxHex(const CTransaction &tx) {
     std::string strHex = EncodeHexTx(tx);
 
-    fprintf(stdout, "%s\n", strHex.c_str());
+    tfm::format(std::cout, "%s\n", strHex.c_str());
 }
 
 static void OutputTx(const CTransaction &tx) {
@@ -871,7 +871,8 @@
     }
 
     if (strPrint != "") {
-        fprintf((nRet == 0 ? stdout : stderr), "%s\n", strPrint.c_str());
+        tfm::format(nRet == 0 ? std::cout : std::cerr, "%s\n",
+                    strPrint.c_str());
     }
 
     return nRet;
diff --git a/src/bitcoin-wallet.cpp b/src/bitcoin-wallet.cpp
--- a/src/bitcoin-wallet.cpp
+++ b/src/bitcoin-wallet.cpp
@@ -50,8 +50,8 @@
     SetupWalletToolArgs();
     std::string error_message;
     if (!gArgs.ParseParameters(argc, argv, error_message)) {
-        fprintf(stderr, "Error parsing command line arguments: %s\n",
-                error_message.c_str());
+        tfm::format(std::cerr, "Error parsing command line arguments: %s\n",
+                    error_message.c_str());
         return false;
     }
     if (argc < 2 || HelpRequested(gArgs)) {
@@ -67,7 +67,7 @@
             "Usage:\n" + "  bitcoin-wallet [options] <command>\n\n" +
             gArgs.GetHelpMessage();
 
-        fprintf(stdout, "%s", usage.c_str());
+        tfm::format(std::cout, "%s", usage.c_str());
         return false;
     }
 
@@ -76,9 +76,9 @@
         gArgs.GetBoolArg("-printtoconsole", gArgs.GetBoolArg("-debug", false));
 
     if (!fs::is_directory(GetDataDir(false))) {
-        fprintf(stderr,
-                "Error: Specified data directory \"%s\" does not exist.\n",
-                gArgs.GetArg("-datadir", "").c_str());
+        tfm::format(std::cerr,
+                    "Error: Specified data directory \"%s\" does not exist.\n",
+                    gArgs.GetArg("-datadir", "").c_str());
         return false;
     }
     // Check for -testnet or -regtest parameter (Params() calls are only valid
@@ -111,10 +111,10 @@
     for (int i = 1; i < argc; ++i) {
         if (!IsSwitchChar(argv[i][0])) {
             if (!method.empty()) {
-                fprintf(stderr,
-                        "Error: two methods provided (%s and %s). Only one "
-                        "method should be provided.\n",
-                        method.c_str(), argv[i]);
+                tfm::format(std::cerr,
+                            "Error: two methods provided (%s and %s). Only one "
+                            "method should be provided.\n",
+                            method.c_str(), argv[i]);
                 return EXIT_FAILURE;
             }
             method = argv[i];
@@ -122,15 +122,17 @@
     }
 
     if (method.empty()) {
-        fprintf(stderr, "No method provided. Run `bitcoin-wallet -help` for "
-                        "valid methods.\n");
+        tfm::format(std::cerr,
+                    "No method provided. Run `bitcoin-wallet -help` for "
+                    "valid methods.\n");
         return EXIT_FAILURE;
     }
 
     // A name must be provided when creating a file
     if (method == "create" && !gArgs.IsArgSet("-wallet")) {
-        fprintf(stderr,
-                "Wallet name must be provided when creating a new wallet.\n");
+        tfm::format(
+            std::cerr,
+            "Wallet name must be provided when creating a new wallet.\n");
         return EXIT_FAILURE;
     }
 
diff --git a/src/bitcoind.cpp b/src/bitcoind.cpp
--- a/src/bitcoind.cpp
+++ b/src/bitcoind.cpp
@@ -83,8 +83,8 @@
     SetupServerArgs();
     std::string error;
     if (!gArgs.ParseParameters(argc, argv, error)) {
-        fprintf(stderr, "Error parsing command line arguments: %s\n",
-                error.c_str());
+        tfm::format(std::cerr, "Error parsing command line arguments: %s\n",
+                    error.c_str());
         return false;
     }
 
@@ -102,20 +102,21 @@
             strUsage += "\n" + gArgs.GetHelpMessage();
         }
 
-        fprintf(stdout, "%s", strUsage.c_str());
+        tfm::format(std::cout, "%s", strUsage.c_str());
         return true;
     }
 
     try {
         if (!fs::is_directory(GetDataDir(false))) {
-            fprintf(stderr,
-                    "Error: Specified data directory \"%s\" does not exist.\n",
-                    gArgs.GetArg("-datadir", "").c_str());
+            tfm::format(
+                std::cerr,
+                "Error: Specified data directory \"%s\" does not exist.\n",
+                gArgs.GetArg("-datadir", "").c_str());
             return false;
         }
         if (!gArgs.ReadConfigFiles(error, true)) {
-            fprintf(stderr, "Error reading configuration file: %s\n",
-                    error.c_str());
+            tfm::format(std::cerr, "Error reading configuration file: %s\n",
+                        error.c_str());
             return false;
         }
         // Check for -testnet or -regtest parameter (Params() calls are only
@@ -123,7 +124,7 @@
         try {
             SelectParams(gArgs.GetChainName());
         } catch (const std::exception &e) {
-            fprintf(stderr, "Error: %s\n", e.what());
+            tfm::format(std::cerr, "Error: %s\n", e.what());
             return false;
         }
 
@@ -141,10 +142,11 @@
         // line
         for (int i = 1; i < argc; i++) {
             if (!IsSwitchChar(argv[i][0])) {
-                fprintf(stderr,
-                        "Error: Command line contains unexpected token '%s', "
-                        "see bitcoind -h for a list of options.\n",
-                        argv[i]);
+                tfm::format(
+                    std::cerr,
+                    "Error: Command line contains unexpected token '%s', "
+                    "see bitcoind -h for a list of options.\n",
+                    argv[i]);
                 return false;
             }
         }
@@ -176,21 +178,21 @@
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 #endif
-            fprintf(stdout, "Bitcoin server starting\n");
+            tfm::format(std::cout, "Bitcoin server starting\n");
 
             // Daemonize
             if (daemon(1, 0)) {
                 // don't chdir (1), do close FDs (0)
-                fprintf(stderr, "Error: daemon() failed: %s\n",
-                        strerror(errno));
+                tfm::format(std::cerr, "Error: daemon() failed: %s\n",
+                            strerror(errno));
                 return false;
             }
 #if defined(MAC_OSX)
 #pragma GCC diagnostic pop
 #endif
 #else
-            fprintf(
-                stderr,
+            tfm::format(
+                std::cerr,
                 "Error: -daemon is not supported on this operating system\n");
             return false;
 #endif // HAVE_DECL_DAEMON
diff --git a/src/init.cpp b/src/init.cpp
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -104,14 +104,13 @@
 }
 
 NODISCARD static bool CreatePidFile() {
-    FILE *file = fsbridge::fopen(GetPidFile(), "w");
+    fsbridge::ofstream file{GetPidFile()};
     if (file) {
 #ifdef WIN32
-        fprintf(file, "%d\n", GetCurrentProcessId());
+        tfm::format(file, "%d\n", GetCurrentProcessId());
 #else
-        fprintf(file, "%d\n", getpid());
+        tfm::format(file, "%d\n", getpid());
 #endif
-        fclose(file);
         return true;
     } else {
         return InitError(strprintf(_("Unable to create the PID file '%s': %s"),
diff --git a/src/noui.cpp b/src/noui.cpp
--- a/src/noui.cpp
+++ b/src/noui.cpp
@@ -45,7 +45,7 @@
     if (!fSecure) {
         LogPrintf("%s: %s\n", strCaption, message);
     }
-    fprintf(stderr, "%s: %s\n", strCaption.c_str(), message.c_str());
+    tfm::format(std::cerr, "%s: %s\n", strCaption.c_str(), message.c_str());
     return false;
 }
 
diff --git a/src/qt/utilitydialog.cpp b/src/qt/utilitydialog.cpp
--- a/src/qt/utilitydialog.cpp
+++ b/src/qt/utilitydialog.cpp
@@ -127,7 +127,7 @@
 void HelpMessageDialog::printToConsole() {
     // On other operating systems, the expected action is to print the message
     // to the console.
-    fprintf(stdout, "%s\n", qPrintable(text));
+    tfm::format(std::cout, "%s\n", qPrintable(text));
 }
 
 void HelpMessageDialog::showOrPrint() {
diff --git a/src/sync.cpp b/src/sync.cpp
--- a/src/sync.cpp
+++ b/src/sync.cpp
@@ -41,9 +41,9 @@
           m_thread_name(thread_name), sourceLine(nLine) {}
 
     std::string ToString() const {
-        return tfm::format("%s %s:%s%s (in thread %s)", mutexName, sourceFile,
-                           itostr(sourceLine), (fTry ? " (TRY)" : ""),
-                           m_thread_name);
+        return strprintf("%s %s:%s%s (in thread %s)", mutexName, sourceFile,
+                         itostr(sourceLine), (fTry ? " (TRY)" : ""),
+                         m_thread_name);
     }
 
 private:
@@ -103,10 +103,11 @@
         LogPrintf(" %s\n", i.second.ToString());
     }
     if (g_debug_lockorder_abort) {
-        fprintf(stderr,
-                "Assertion failed: detected inconsistent lock order at %s:%i, "
-                "details in debug log.\n",
-                __FILE__, __LINE__);
+        tfm::format(
+            std::cerr,
+            "Assertion failed: detected inconsistent lock order at %s:%i, "
+            "details in debug log.\n",
+            __FILE__, __LINE__);
         abort();
     }
     throw std::logic_error("potential deadlock detected");
@@ -167,9 +168,9 @@
             return;
         }
     }
-    fprintf(stderr,
-            "Assertion failed: lock %s not held in %s:%i; locks held:\n%s",
-            pszName, pszFile, nLine, LocksHeld().c_str());
+    tfm::format(std::cerr,
+                "Assertion failed: lock %s not held in %s:%i; locks held:\n%s",
+                pszName, pszFile, nLine, LocksHeld().c_str());
     abort();
 }
 
@@ -177,9 +178,10 @@
                                int nLine, void *cs) {
     for (const std::pair<void *, CLockLocation> &i : g_lockstack) {
         if (i.first == cs) {
-            fprintf(stderr,
-                    "Assertion failed: lock %s held in %s:%i; locks held:\n%s",
-                    pszName, pszFile, nLine, LocksHeld().c_str());
+            tfm::format(
+                std::cerr,
+                "Assertion failed: lock %s held in %s:%i; locks held:\n%s",
+                pszName, pszFile, nLine, LocksHeld().c_str());
             abort();
         }
     }
diff --git a/src/tinyformat.h b/src/tinyformat.h
--- a/src/tinyformat.h
+++ b/src/tinyformat.h
@@ -1085,6 +1085,8 @@
 
 } // namespace tinyformat
 
+/** Format arguments and return the string or write to given std::ostream (see
+ * tinyformat::format doc for details) */
 #define strprintf tfm::format
 
 #endif // TINYFORMAT_H_INCLUDED
diff --git a/src/util/system.cpp b/src/util/system.cpp
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -779,7 +779,8 @@
 void PrintExceptionContinue(const std::exception *pex, const char *pszThread) {
     std::string message = FormatException(pex, pszThread);
     LogPrintf("\n\n************************\n%s\n", message);
-    fprintf(stderr, "\n\n************************\n%s\n", message.c_str());
+    tfm::format(std::cerr, "\n\n************************\n%s\n",
+                message.c_str());
 }
 
 fs::path GetDefaultDataDir() {
@@ -1072,10 +1073,11 @@
                 }
             }
             for (const std::string &to_include : includeconf) {
-                fprintf(stderr,
-                        "warning: -includeconf cannot be used from included "
-                        "files; ignoring -includeconf=%s\n",
-                        to_include.c_str());
+                tfm::format(
+                    std::cerr,
+                    "warning: -includeconf cannot be used from included "
+                    "files; ignoring -includeconf=%s\n",
+                    to_include.c_str());
             }
         }
     }
diff --git a/src/wallet/wallettool.cpp b/src/wallet/wallettool.cpp
--- a/src/wallet/wallettool.cpp
+++ b/src/wallet/wallettool.cpp
@@ -26,7 +26,7 @@
 static std::shared_ptr<CWallet> CreateWallet(const std::string &name,
                                              const fs::path &path) {
     if (fs::exists(path)) {
-        fprintf(stderr, "Error: File exists already\n");
+        tfm::format(std::cerr, "Error: File exists already\n");
         return nullptr;
     }
     // dummy chain interface
@@ -38,7 +38,7 @@
     bool first_run = true;
     DBErrors load_wallet_ret = wallet_instance->LoadWallet(first_run);
     if (load_wallet_ret != DBErrors::LOAD_OK) {
-        fprintf(stderr, "Error creating %s", name.c_str());
+        tfm::format(std::cerr, "Error creating %s", name.c_str());
         return nullptr;
     }
 
@@ -48,7 +48,7 @@
     CPubKey seed = wallet_instance->GenerateNewSeed();
     wallet_instance->SetHDSeed(seed);
 
-    fprintf(stdout, "Topping up keypool...\n");
+    tfm::format(std::cout, "Topping up keypool...\n");
     wallet_instance->TopUpKeyPool();
     return wallet_instance;
 }
@@ -56,7 +56,7 @@
 static std::shared_ptr<CWallet> LoadWallet(const std::string &name,
                                            const fs::path &path) {
     if (!fs::exists(path)) {
-        fprintf(stderr, "Error: Wallet files does not exist\n");
+        tfm::format(std::cerr, "Error: Wallet files does not exist\n");
         return nullptr;
     }
 
@@ -71,35 +71,38 @@
         bool first_run;
         load_wallet_ret = wallet_instance->LoadWallet(first_run);
     } catch (const std::runtime_error &) {
-        fprintf(stderr,
-                "Error loading %s. Is wallet being used by another process?\n",
-                name.c_str());
+        tfm::format(
+            std::cerr,
+            "Error loading %s. Is wallet being used by another process?\n",
+            name.c_str());
         return nullptr;
     }
 
     if (load_wallet_ret != DBErrors::LOAD_OK) {
         wallet_instance = nullptr;
         if (load_wallet_ret == DBErrors::CORRUPT) {
-            fprintf(stderr, "Error loading %s: Wallet corrupted", name.c_str());
+            tfm::format(std::cerr, "Error loading %s: Wallet corrupted",
+                        name.c_str());
             return nullptr;
         } else if (load_wallet_ret == DBErrors::NONCRITICAL_ERROR) {
-            fprintf(stderr,
-                    "Error reading %s! All keys read correctly, but "
-                    "transaction data"
-                    " or address book entries might be missing or incorrect.",
-                    name.c_str());
+            tfm::format(
+                std::cerr,
+                "Error reading %s! All keys read correctly, but "
+                "transaction data"
+                " or address book entries might be missing or incorrect.",
+                name.c_str());
         } else if (load_wallet_ret == DBErrors::TOO_NEW) {
-            fprintf(stderr,
-                    "Error loading %s: Wallet requires newer version of %s",
-                    name.c_str(), PACKAGE_NAME);
+            tfm::format(std::cerr,
+                        "Error loading %s: Wallet requires newer version of %s",
+                        name.c_str(), PACKAGE_NAME);
             return nullptr;
         } else if (load_wallet_ret == DBErrors::NEED_REWRITE) {
-            fprintf(stderr,
-                    "Wallet needed to be rewritten: restart %s to complete",
-                    PACKAGE_NAME);
+            tfm::format(std::cerr,
+                        "Wallet needed to be rewritten: restart %s to complete",
+                        PACKAGE_NAME);
             return nullptr;
         } else {
-            fprintf(stderr, "Error loading %s", name.c_str());
+            tfm::format(std::cerr, "Error loading %s", name.c_str());
             return nullptr;
         }
     }
@@ -111,15 +114,17 @@
     // lock required because of some AssertLockHeld()
     LOCK(wallet_instance->cs_wallet);
 
-    fprintf(stdout, "Wallet info\n===========\n");
-    fprintf(stdout, "Encrypted: %s\n",
-            wallet_instance->IsCrypted() ? "yes" : "no");
-    fprintf(stdout, "HD (hd seed available): %s\n",
-            wallet_instance->GetHDChain().seed_id.IsNull() ? "no" : "yes");
-    fprintf(stdout, "Keypool Size: %u\n", wallet_instance->GetKeyPoolSize());
-    fprintf(stdout, "Transactions: %zu\n", wallet_instance->mapWallet.size());
-    fprintf(stdout, "Address Book: %zu\n",
-            wallet_instance->mapAddressBook.size());
+    tfm::format(std::cout, "Wallet info\n===========\n");
+    tfm::format(std::cout, "Encrypted: %s\n",
+                wallet_instance->IsCrypted() ? "yes" : "no");
+    tfm::format(std::cout, "HD (hd seed available): %s\n",
+                wallet_instance->GetHDChain().seed_id.IsNull() ? "no" : "yes");
+    tfm::format(std::cout, "Keypool Size: %u\n",
+                wallet_instance->GetKeyPoolSize());
+    tfm::format(std::cout, "Transactions: %zu\n",
+                wallet_instance->mapWallet.size());
+    tfm::format(std::cout, "Address Book: %zu\n",
+                wallet_instance->mapAddressBook.size());
 }
 
 bool ExecuteWalletToolFunc(const std::string &command,
@@ -134,13 +139,14 @@
         }
     } else if (command == "info") {
         if (!fs::exists(path)) {
-            fprintf(stderr, "Error: no wallet file at %s\n", name.c_str());
+            tfm::format(std::cerr, "Error: no wallet file at %s\n",
+                        name.c_str());
             return false;
         }
         std::string error;
         if (!WalletBatch::VerifyEnvironment(path, error)) {
-            fprintf(
-                stderr,
+            tfm::format(
+                std::cerr,
                 "Error loading %s. Is wallet being used by other process?\n",
                 name.c_str());
             return false;
@@ -152,7 +158,7 @@
         WalletShowInfo(wallet_instance.get());
         wallet_instance->Flush();
     } else {
-        fprintf(stderr, "Invalid command: %s\n", command.c_str());
+        tfm::format(std::cerr, "Invalid command: %s\n", command.c_str());
         return false;
     }
 
diff --git a/test/lint/lint-format-strings.py b/test/lint/lint-format-strings.py
--- a/test/lint/lint-format-strings.py
+++ b/test/lint/lint-format-strings.py
@@ -37,6 +37,7 @@
     ("snprintf", 2),
     ("sprintf", 1),
     ("strprintf", 0),
+    ("tfm::format", 1),  # Assuming tfm::::format(std::ostream&, ...
     ("vfprintf", 1),
     ("vprintf", 1),
     ("vsnprintf", 1),