diff --git a/apps/opencs/model/filter/parser.cpp b/apps/opencs/model/filter/parser.cpp
index b8f125e237..d363b4849d 100644
--- a/apps/opencs/model/filter/parser.cpp
+++ b/apps/opencs/model/filter/parser.cpp
@@ -17,19 +17,6 @@
 #include "textnode.hpp"
 #include "valuenode.hpp"
 
-namespace
-{
-    bool isAlpha(char c)
-    {
-        return c >= 0 && c <= 255 && std::isalpha(c);
-    }
-
-    bool isDigit(char c)
-    {
-        return c >= 0 && c <= 255 && std::isdigit(c);
-    }
-}
-
 namespace CSMFilter
 {
     struct Token
@@ -116,7 +103,7 @@ CSMFilter::Token CSMFilter::Parser::getStringToken()
     {
         char c = mInput[mIndex];
 
-        if (isAlpha(c) || c==':' || c=='_' || (!string.empty() && isDigit(c)) || c=='"' ||
+        if (std::isalpha (c) || c==':' || c=='_' || (!string.empty() && std::isdigit (c)) || c=='"' ||
             (!string.empty() && string[0]=='"'))
             string += c;
         else
@@ -163,7 +150,7 @@ CSMFilter::Token CSMFilter::Parser::getNumberToken()
     {
         char c = mInput[mIndex];
 
-        if (isDigit(c))
+        if (std::isdigit (c))
         {
             string += c;
             hasDigit = true;
@@ -238,10 +225,10 @@ CSMFilter::Token CSMFilter::Parser::getNextToken()
         case '!': ++mIndex; return Token (Token::Type_OneShot);
     }
 
-    if (c=='"' || c=='_' || isAlpha(c) || c==':')
+    if (c=='"' || c=='_' || std::isalpha (c) || c==':')
         return getStringToken();
 
-    if (c=='-' || c=='.' || isDigit(c))
+    if (c=='-' || c=='.' || std::isdigit (c))
         return getNumberToken();
 
     error();
diff --git a/components/lua/configuration.cpp b/components/lua/configuration.cpp
index d059d1716f..4598ed2508 100644
--- a/components/lua/configuration.cpp
+++ b/components/lua/configuration.cpp
@@ -30,11 +30,6 @@ namespace LuaUtil
             {"POTION", ESM::LuaScriptCfg::sPotion},
             {"WEAPON", ESM::LuaScriptCfg::sWeapon},
         };
-
-        bool isSpace(int c)
-        {
-            return c >= 0 && c <= 255 && std::isspace(c);
-        }
     }
 
     const std::vector<int> ScriptsConfiguration::sEmpty;
@@ -106,11 +101,11 @@ namespace LuaUtil
             if (!line.empty() && line.back() == '\r')
                 line = line.substr(0, line.size() - 1);
 
-            while (!line.empty() && isSpace(line[0]))
+            while (!line.empty() && std::isspace(line[0]))
                 line = line.substr(1);
             if (line.empty() || line[0] == '#')  // Skip empty lines and comments
                 continue;
-            while (!line.empty() && isSpace(line.back()))
+            while (!line.empty() && std::isspace(line.back()))
                 line = line.substr(0, line.size() - 1);
 
             if (!Misc::StringUtils::ciEndsWith(line, ".lua"))
@@ -123,7 +118,7 @@ namespace LuaUtil
                 throw std::runtime_error(Misc::StringUtils::format("No flags found in: %s", std::string(line)));
             std::string_view flagsStr = line.substr(0, semicolonPos);
             std::string_view scriptPath = line.substr(semicolonPos + 1);
-            while (isSpace(scriptPath[0]))
+            while (std::isspace(scriptPath[0]))
                 scriptPath = scriptPath.substr(1);
 
             // Parse flags
@@ -131,10 +126,10 @@ namespace LuaUtil
             size_t flagsPos = 0;
             while (true)
             {
-                while (flagsPos < flagsStr.size() && (isSpace(flagsStr[flagsPos]) || flagsStr[flagsPos] == ','))
+                while (flagsPos < flagsStr.size() && (std::isspace(flagsStr[flagsPos]) || flagsStr[flagsPos] == ','))
                     flagsPos++;
                 size_t startPos = flagsPos;
-                while (flagsPos < flagsStr.size() && !isSpace(flagsStr[flagsPos]) && flagsStr[flagsPos] != ',')
+                while (flagsPos < flagsStr.size() && !std::isspace(flagsStr[flagsPos]) && flagsStr[flagsPos] != ',')
                     flagsPos++;
                 if (startPos == flagsPos)
                     break;
diff --git a/components/misc/stringops.hpp b/components/misc/stringops.hpp
index a0ec9f62dd..c8d236a9d0 100644
--- a/components/misc/stringops.hpp
+++ b/components/misc/stringops.hpp
@@ -184,10 +184,10 @@ public:
 
     static inline void trim(std::string &s)
     {
-        const auto notSpace = [](int ch)
+        const auto notSpace = [](char ch)
         {
             // TODO Do we care about multibyte whitespace?
-            return ch < 0 || ch > 255 || !std::isspace(ch);
+            return !std::isspace(ch);
         };
         // left trim
         s.erase(s.begin(), std::find_if(s.begin(), s.end(), notSpace));
diff --git a/components/settings/parser.cpp b/components/settings/parser.cpp
index f36f190ee2..f2419dfdd6 100644
--- a/components/settings/parser.cpp
+++ b/components/settings/parser.cpp
@@ -311,7 +311,7 @@ void Settings::SettingsFileParser::saveSettingsFile(const std::string& file, con
 
 bool Settings::SettingsFileParser::skipWhiteSpace(size_t& i, std::string& str)
 {
-    while (i < str.size() && str[i] >= 0 && str[i] <= 255 && std::isspace(str[i], std::locale::classic()))
+    while (i < str.size() && std::isspace(str[i], std::locale::classic()))
     {
         ++i;
     }