diff --git a/arcanist/linter/LocaleDependenceLinter.php b/arcanist/linter/LocaleDependenceLinter.php
--- a/arcanist/linter/LocaleDependenceLinter.php
+++ b/arcanist/linter/LocaleDependenceLinter.php
@@ -11,9 +11,7 @@
     "src/bitcoin-tx.cpp" => [
       "stoul",
       "trim_right",
-      "atoi",
     ],
-    "src/core_read.cpp" => ["is_digit"],
     "src/dbwrapper.cpp" => [
         "stoul",
         "vsnprintf"
@@ -23,7 +21,6 @@
     "src/netbase.cpp" => ["to_lower"],
     "src/qt/rpcconsole.cpp" => [
       "atoi",
-      "isdigit",
     ],
     "src/rest.cpp" => ["strtol"],
     "src/rpc/server.cpp" => ["to_upper"],
@@ -42,9 +39,7 @@
       "atoi",
       "strtol",
     ],
-    "src/uint256.cpp" => ["tolower"],
-    "src/util/system.cpp" => ["atoi", "tolower"],
-    "src/util/moneystr.cpp" => ["isdigit"],
+    "src/util/system.cpp" => ["atoi"],
     "src/util/strencodings.cpp" => [
       "atoi",
       "strtol",
diff --git a/src/qt/rpcconsole.cpp b/src/qt/rpcconsole.cpp
--- a/src/qt/rpcconsole.cpp
+++ b/src/qt/rpcconsole.cpp
@@ -20,6 +20,7 @@
 #include <qt/walletmodel.h>
 #include <rpc/client.h>
 #include <rpc/server.h>
+#include <util/strencodings.h>
 #include <util/system.h>
 
 #ifdef ENABLE_WALLET
@@ -229,7 +230,7 @@
                                 UniValue subelement;
                                 if (lastResult.isArray()) {
                                     for (char argch : curarg) {
-                                        if (!std::isdigit(argch)) {
+                                        if (!IsDigit(argch)) {
                                             throw std::runtime_error(
                                                 "Invalid result query");
                                         }
diff --git a/src/test/getarg_tests.cpp b/src/test/getarg_tests.cpp
--- a/src/test/getarg_tests.cpp
+++ b/src/test/getarg_tests.cpp
@@ -2,6 +2,7 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#include <util/strencodings.h>
 #include <util/system.h>
 
 #include <test/setup_common.h>
@@ -20,8 +21,7 @@
 static void ResetArgs(ArgsManager &am, const std::string &strArg) {
     std::vector<std::string> vecArg;
     if (strArg.size()) {
-        boost::split(vecArg, strArg, boost::is_space(),
-                     boost::token_compress_on);
+        boost::split(vecArg, strArg, IsSpace, boost::token_compress_on);
     }
 
     // Insert dummy executable name:
diff --git a/src/uint256.cpp b/src/uint256.cpp
--- a/src/uint256.cpp
+++ b/src/uint256.cpp
@@ -30,7 +30,7 @@
     }
 
     // skip 0x
-    if (psz[0] == '0' && tolower(psz[1]) == 'x') {
+    if (psz[0] == '0' && ToLower(uint8_t(psz[1])) == 'x') {
         psz += 2;
     }
 
diff --git a/src/util/moneystr.cpp b/src/util/moneystr.cpp
--- a/src/util/moneystr.cpp
+++ b/src/util/moneystr.cpp
@@ -18,7 +18,7 @@
 
     // Right-trim excess zeros before the decimal point:
     int nTrim = 0;
-    for (int i = str.size() - 1; (str[i] == '0' && isdigit(str[i - 2])); --i) {
+    for (int i = str.size() - 1; (str[i] == '0' && IsDigit(str[i - 2])); --i) {
         ++nTrim;
     }
     if (nTrim) {
@@ -46,7 +46,7 @@
         if (*p == '.') {
             p++;
             Amount nMult = COIN / 10;
-            while (isdigit(*p) && (nMult > Amount::zero())) {
+            while (IsDigit(*p) && (nMult > Amount::zero())) {
                 nUnits += (*p++ - '0') * nMult;
                 nMult /= 10;
             }
@@ -55,7 +55,7 @@
         if (IsSpace(*p)) {
             break;
         }
-        if (!isdigit(*p)) {
+        if (!IsDigit(*p)) {
             return false;
         }
         strWhole.insert(strWhole.end(), *p);
diff --git a/src/util/system.cpp b/src/util/system.cpp
--- a/src/util/system.cpp
+++ b/src/util/system.cpp
@@ -304,7 +304,7 @@
         key.erase(is_index);
     }
 #ifdef WIN32
-    std::transform(key.begin(), key.end(), key.begin(), ::tolower);
+    std::transform(key.begin(), key.end(), key.begin(), ToLower);
     if (key[0] == '/') {
         key[0] = '-';
     }