diff --git a/README.md b/README.md
index 01f0f195..1c46686b 100644
--- a/README.md
+++ b/README.md
@@ -255,6 +255,14 @@ On the command line, options can be given as:
 -   `--file filename` (space)
 -   `--file=filename` (equals)
 
+If allow_windows_style_options() is specified in the application or subcommand options can also be given as:
+-   `/a` (flag)
+-   `/f filename` (option)
+-   `/long` (long flag)
+-   `/file filename` (space)
+-   `/file:filename` (colon)
+=  Windows style options do not allow combining short options or values not separated from the short option like with `-` options
+
 Extra positional arguments will cause the program to exit, so at least one positional option with a vector is recommended if you want to allow extraneous arguments.
 If you set `.allow_extras()` on the main `App`, you will not get an error. You can access the missing options using `remaining` (if you have subcommands, `app.remaining(true)` will get all remaining options, subcommands included).
 
@@ -285,7 +293,7 @@ There are several options that are supported on the main app and subcommands. Th
 
 -   `.ignore_case()`: Ignore the case of this subcommand. Inherited by added subcommands, so is usually used on the main `App`.
 -   `.ignore_underscore()`: Ignore any underscores in the subcommand name. Inherited by added subcommands, so is usually used on the main `App`.
-
+-   `.allow_windows_style_options()`:  Allow command line options to be parsed in the form of `/s /long /file:file_name.ext`  This option does not change how options are specified in the `add_option` calls or the ability to process options in the form of `-s --long --file=file_name.ext`
 -   `.fallthrough()`: Allow extra unmatched options and positionals to "fall through" and be matched on a parent command. Subcommands always are allowed to fall through.
 -   `.require_subcommand()`: Require 1 or more subcommands.
 -   `.require_subcommand(N)`: Require `N` subcommands if `N>0`, or up to `N` if `N<0`. `N=0` resets to the default 0 or more.
diff --git a/include/CLI/App.hpp b/include/CLI/App.hpp
index d773e01a..5f420edc 100644
--- a/include/CLI/App.hpp
+++ b/include/CLI/App.hpp
@@ -38,7 +38,7 @@ namespace CLI {
 #endif
 
 namespace detail {
-enum class Classifer { NONE, POSITIONAL_MARK, SHORT, LONG, SUBCOMMAND };
+enum class Classifier { NONE, POSITIONAL_MARK, SHORT, LONG, WINDOWS, SUBCOMMAND };
 struct AppFriend;
 } // namespace detail
 
@@ -116,7 +116,7 @@ class App {
     /// @name Parsing
     ///@{
 
-    using missing_t = std::vector<std::pair<detail::Classifer, std::string>>;
+    using missing_t = std::vector<std::pair<detail::Classifier, std::string>>;
 
     /// Pair of classifier, string for missing options. (extra detail is removed on returning from parse)
     ///
@@ -145,6 +145,9 @@ class App {
     /// Allow subcommand fallthrough, so that parent commands can collect commands after subcommand.  INHERITABLE
     bool fallthrough_{false};
 
+    /// Allow '/' for options for windows like options INHERITABLE
+    bool allow_windows_style_options_{false};
+
     /// A pointer to the parent if this is a subcommand
     App *parent_{nullptr};
 
@@ -200,6 +203,7 @@ class App {
             ignore_case_ = parent_->ignore_case_;
             ignore_underscore_ = parent_->ignore_underscore_;
             fallthrough_ = parent_->fallthrough_;
+            allow_windows_style_options_ = parent_->allow_windows_style_options_;
             group_ = parent_->group_;
             footer_ = parent_->footer_;
             formatter_ = parent_->formatter_;
@@ -251,7 +255,7 @@ class App {
         return this;
     }
 
-    /// Do not parse anything after the first unrecognised option and return
+    /// Do not parse anything after the first unrecognized option and return
     App *prefix_command(bool allow = true) {
         prefix_command_ = allow;
         return this;
@@ -269,6 +273,12 @@ class App {
         return this;
     }
 
+    /// Ignore case. Subcommand inherit value.
+    App *allow_windows_style_options(bool value = true) {
+        allow_windows_style_options_ = value;
+        return this;
+    }
+
     /// Ignore underscore. Subcommand inherit value.
     App *ignore_underscore(bool value = true) {
         ignore_underscore_ = value;
@@ -1172,43 +1182,32 @@ class App {
     /// the function takes an optional boolean argument specifying if the programName is included in the string to
     /// process
     void parse(std::string commandline, bool program_name_included = false) {
-        detail::trim(commandline);
+
         if(program_name_included) {
-            // try to determine the programName
-            auto esp = commandline.find_first_of(' ', 1);
-            while(!ExistingFile(commandline.substr(0, esp)).empty()) {
-                esp = commandline.find_first_of(' ', esp + 1);
-                if(esp == std::string::npos) {
-                    // if we have reached the end and haven't found a valid file just assume the first argument is the
-                    // program name
-                    esp = commandline.find_first_of(' ', 1);
-                    break;
-                }
-            }
+            auto nstr = detail::split_program_name(commandline);
             if(name_.empty()) {
-                name_ = commandline.substr(0, esp);
-                detail::rtrim(name_);
+                name_ = nstr.first;
             }
-            // strip the program name
-            commandline = commandline.substr(esp + 1);
-        }
-        // the first section of code is to deal with quoted arguments after and '='
+            commandline = std::move(nstr.second);
+        } else
+            detail::trim(commandline);
+        // the next section of code is to deal with quoted arguments after an '=' or ':' for windows like operations
         if(!commandline.empty()) {
-            size_t offset = commandline.length() - 1;
-            auto qeq = commandline.find_last_of('=', offset);
-            while(qeq != std::string::npos) {
-                if((commandline[qeq + 1] == '\"') || (commandline[qeq + 1] == '\'') || (commandline[qeq + 1] == '`')) {
-                    auto astart = commandline.find_last_of("- \"\'`", qeq - 1);
+            auto escape_detect = [](std::string &str, size_t offset) {
+                auto next = str[offset + 1];
+                if((next == '\"') || (next == '\'') || (next == '`')) {
+                    auto astart = str.find_last_of("-/ \"\'`", offset - 1);
                     if(astart != std::string::npos) {
-                        if(commandline[astart] == '-') {
-                            commandline[qeq] = ' '; // interpret this a space so the split_up works properly
-                            offset = (astart == 0) ? 0 : (astart - 1);
-                        }
+                        if(str[astart] == (str[offset] == '=') ? '-' : '/')
+                            str[offset] = ' '; // interpret this as a space so the split_up works properly
                     }
                 }
-                offset = qeq - 1;
-                qeq = commandline.find_last_of('=', offset);
-            }
+                return (offset + 1);
+            };
+
+            commandline = detail::find_and_modify(commandline, "=", escape_detect);
+            if(allow_windows_style_options_)
+                commandline = detail::find_and_modify(commandline, ":", escape_detect);
         }
 
         auto args = detail::split_up(std::move(commandline));
@@ -1339,8 +1338,8 @@ class App {
         return this;
     }
 
-    /// Produce a string that could be read in as a config of the current values of the App. Set default_also to include
-    /// default arguments. Prefix will add a string to the beginning of each option.
+    /// Produce a string that could be read in as a config of the current values of the App. Set default_also to
+    /// include default arguments. Prefix will add a string to the beginning of each option.
     std::string config_to_str(bool default_also = false, bool write_description = false) const {
         return config_formatter_->to_config(this, default_also, write_description, "");
     }
@@ -1432,6 +1431,9 @@ class App {
     /// Check the status of fallthrough
     bool get_fallthrough() const { return fallthrough_; }
 
+    /// Check the status of the allow windows style options
+    bool get_allow_windows_style_options() const { return allow_windows_style_options_; }
+
     /// Get the group of this subcommand
     const std::string &get_group() const { return group_; }
 
@@ -1512,7 +1514,7 @@ class App {
     /// This returns the missing options from the current subcommand
     std::vector<std::string> remaining(bool recurse = false) const {
         std::vector<std::string> miss_list;
-        for(const std::pair<detail::Classifer, std::string> &miss : missing_) {
+        for(const std::pair<detail::Classifier, std::string> &miss : missing_) {
             miss_list.push_back(std::get<1>(miss));
         }
 
@@ -1526,11 +1528,11 @@ class App {
         return miss_list;
     }
 
-    /// This returns the number of remaining options, minus the -- seperator
+    /// This returns the number of remaining options, minus the -- separator
     size_t remaining_size(bool recurse = false) const {
         auto count = static_cast<size_t>(std::count_if(
-            std::begin(missing_), std::end(missing_), [](const std::pair<detail::Classifer, std::string> &val) {
-                return val.first != detail::Classifer::POSITIONAL_MARK;
+            std::begin(missing_), std::end(missing_), [](const std::pair<detail::Classifier, std::string> &val) {
+                return val.first != detail::Classifier::POSITIONAL_MARK;
             }));
         if(recurse) {
             for(const App_p &sub : subcommands_) {
@@ -1582,18 +1584,20 @@ class App {
     }
 
     /// Selects a Classifier enum based on the type of the current argument
-    detail::Classifer _recognize(const std::string &current) const {
+    detail::Classifier _recognize(const std::string &current) const {
         std::string dummy1, dummy2;
 
         if(current == "--")
-            return detail::Classifer::POSITIONAL_MARK;
+            return detail::Classifier::POSITIONAL_MARK;
         if(_valid_subcommand(current))
-            return detail::Classifer::SUBCOMMAND;
+            return detail::Classifier::SUBCOMMAND;
         if(detail::split_long(current, dummy1, dummy2))
-            return detail::Classifer::LONG;
+            return detail::Classifier::LONG;
         if(detail::split_short(current, dummy1, dummy2))
-            return detail::Classifer::SHORT;
-        return detail::Classifer::NONE;
+            return detail::Classifier::SHORT;
+        if((allow_windows_style_options_) && (detail::split_windows(current, dummy1, dummy2)))
+            return detail::Classifier::WINDOWS;
+        return detail::Classifier::NONE;
     }
 
     // The parse function is now broken into several parts, and part of process
@@ -1800,7 +1804,7 @@ class App {
             // If the option was not present
             if(get_allow_config_extras())
                 // Should we worry about classifying the extras properly?
-                missing_.emplace_back(detail::Classifer::NONE, item.fullname());
+                missing_.emplace_back(detail::Classifier::NONE, item.fullname());
             return false;
         }
 
@@ -1820,29 +1824,27 @@ class App {
         return true;
     }
 
-    /// Parse "one" argument (some may eat more than one), delegate to parent if fails, add to missing if missing from
-    /// master
+    /// Parse "one" argument (some may eat more than one), delegate to parent if fails, add to missing if missing
+    /// from master
     void _parse_single(std::vector<std::string> &args, bool &positional_only) {
 
-        detail::Classifer classifer = positional_only ? detail::Classifer::NONE : _recognize(args.back());
-        switch(classifer) {
-        case detail::Classifer::POSITIONAL_MARK:
-            missing_.emplace_back(classifer, args.back());
+        detail::Classifier classifier = positional_only ? detail::Classifier::NONE : _recognize(args.back());
+        switch(classifier) {
+        case detail::Classifier::POSITIONAL_MARK:
+            missing_.emplace_back(classifier, args.back());
             args.pop_back();
             positional_only = true;
             break;
-        case detail::Classifer::SUBCOMMAND:
+        case detail::Classifier::SUBCOMMAND:
             _parse_subcommand(args);
             break;
-        case detail::Classifer::LONG:
+        case detail::Classifier::LONG:
+        case detail::Classifier::SHORT:
+        case detail::Classifier::WINDOWS:
             // If already parsed a subcommand, don't accept options_
-            _parse_arg(args, true);
+            _parse_arg(args, classifier);
             break;
-        case detail::Classifer::SHORT:
-            // If already parsed a subcommand, don't accept options_
-            _parse_arg(args, false);
-            break;
-        case detail::Classifer::NONE:
+        case detail::Classifier::NONE:
             // Probably a positional or something for a parent (sub)command
             _parse_positional(args);
         }
@@ -1879,11 +1881,11 @@ class App {
             return parent_->_parse_positional(args);
         else {
             args.pop_back();
-            missing_.emplace_back(detail::Classifer::NONE, positional);
+            missing_.emplace_back(detail::Classifier::NONE, positional);
 
             if(prefix_command_) {
                 while(!args.empty()) {
-                    missing_.emplace_back(detail::Classifer::NONE, args.back());
+                    missing_.emplace_back(detail::Classifier::NONE, args.back());
                     args.pop_back();
                 }
             }
@@ -1913,9 +1915,7 @@ class App {
     }
 
     /// Parse a short (false) or long (true) argument, must be at the top of the list
-    void _parse_arg(std::vector<std::string> &args, bool second_dash) {
-
-        detail::Classifer current_type = second_dash ? detail::Classifer::LONG : detail::Classifer::SHORT;
+    void _parse_arg(std::vector<std::string> &args, detail::Classifier current_type) {
 
         std::string current = args.back();
 
@@ -1923,23 +1923,37 @@ class App {
         std::string value;
         std::string rest;
 
-        if(second_dash) {
+        switch(current_type) {
+        case detail::Classifier::LONG:
             if(!detail::split_long(current, name, value))
                 throw HorribleError("Long parsed but missing (you should not see this):" + args.back());
-        } else {
+            break;
+        case detail::Classifier::SHORT:
             if(!detail::split_short(current, name, rest))
                 throw HorribleError("Short parsed but missing! You should not see this");
+            break;
+        case detail::Classifier::WINDOWS:
+            if(!detail::split_windows(current, name, value))
+                throw HorribleError("windows option parsed but missing! You should not see this");
+            break;
+        default:
+            throw HorribleError("parsing got called with invalid option! You should not see this");
         }
 
-        auto op_ptr = std::find_if(std::begin(options_), std::end(options_), [name, second_dash](const Option_p &opt) {
-            return second_dash ? opt->check_lname(name) : opt->check_sname(name);
+        auto op_ptr = std::find_if(std::begin(options_), std::end(options_), [name, current_type](const Option_p &opt) {
+            if(current_type == detail::Classifier::LONG)
+                return opt->check_lname(name);
+            if(current_type == detail::Classifier::SHORT)
+                return opt->check_sname(name);
+            // this will only get called for detail::Classifier::WINDOWS
+            return opt->check_lname(name) || opt->check_sname(name);
         });
 
         // Option not found
         if(op_ptr == std::end(options_)) {
             // If a subcommand, try the master command
             if(parent_ != nullptr && fallthrough_)
-                return parent_->_parse_arg(args, second_dash);
+                return parent_->_parse_arg(args, current_type);
             // Otherwise, add to missing
             else {
                 args.pop_back();
@@ -1981,7 +1995,7 @@ class App {
 
         // Unlimited vector parser
         if(num < 0) {
-            while(!args.empty() && _recognize(args.back()) == detail::Classifer::NONE) {
+            while(!args.empty() && _recognize(args.back()) == detail::Classifier::NONE) {
                 if(collected >= -num) {
                     // We could break here for allow extras, but we don't
 
@@ -1996,7 +2010,7 @@ class App {
             }
 
             // Allow -- to end an unlimited list and "eat" it
-            if(!args.empty() && _recognize(args.back()) == detail::Classifer::POSITIONAL_MARK)
+            if(!args.empty() && _recognize(args.back()) == detail::Classifier::POSITIONAL_MARK)
                 args.pop_back();
 
         } else {
diff --git a/include/CLI/Formatter.hpp b/include/CLI/Formatter.hpp
index 7f1885ec..df37279f 100644
--- a/include/CLI/Formatter.hpp
+++ b/include/CLI/Formatter.hpp
@@ -115,7 +115,7 @@ inline std::string Formatter::make_footer(const App *app) const {
 
 inline std::string Formatter::make_help(const App *app, std::string name, AppFormatMode mode) const {
 
-    // This immediatly forwards to the make_expanded method. This is done this way so that subcommands can
+    // This immediately forwards to the make_expanded method. This is done this way so that subcommands can
     // have overridden formatters
     if(mode == AppFormatMode::Sub)
         return make_expanded(app);
diff --git a/include/CLI/Option.hpp b/include/CLI/Option.hpp
index f858ed6c..9da3450a 100644
--- a/include/CLI/Option.hpp
+++ b/include/CLI/Option.hpp
@@ -479,7 +479,7 @@ class Option : public OptionBase<Option> {
     int get_expected() const { return expected_; }
 
     /// \brief The total number of expected values (including the type)
-    /// This is positive if exactly this number is expected, and negitive for at least N values
+    /// This is positive if exactly this number is expected, and negative for at least N values
     ///
     /// v = fabs(size_type*expected)
     /// !MultiOptionPolicy::Throw
@@ -518,7 +518,7 @@ class Option : public OptionBase<Option> {
     /// @name Help tools
     ///@{
 
-    /// \brief Gets a comma seperated list of names.
+    /// \brief Gets a comma separated list of names.
     /// Will include / prefer the positional name if positional is true.
     /// If all_options is false, pick just the most descriptive name to show.
     /// Use `get_name(true)` to get the positional name (replaces `get_pname`)
@@ -530,7 +530,7 @@ class Option : public OptionBase<Option> {
 
             std::vector<std::string> name_list;
 
-            /// The all list wil never include a positional unless asked or that's the only name.
+            /// The all list will never include a positional unless asked or that's the only name.
             if((positional && pname_.length()) || (snames_.empty() && lnames_.empty()))
                 name_list.push_back(pname_);
 
diff --git a/include/CLI/Split.hpp b/include/CLI/Split.hpp
index 8a1666cb..f2ec3525 100644
--- a/include/CLI/Split.hpp
+++ b/include/CLI/Split.hpp
@@ -26,7 +26,7 @@ inline bool split_short(const std::string &current, std::string &name, std::stri
 // Returns false if not a long option. Otherwise, sets opt name and other side of = and returns true
 inline bool split_long(const std::string &current, std::string &name, std::string &value) {
     if(current.size() > 2 && current.substr(0, 2) == "--" && valid_first_char(current[2])) {
-        auto loc = current.find("=");
+        auto loc = current.find_first_of('=');
         if(loc != std::string::npos) {
             name = current.substr(2, loc - 2);
             value = current.substr(loc + 1);
@@ -39,6 +39,22 @@ inline bool split_long(const std::string &current, std::string &name, std::strin
         return false;
 }
 
+// Returns false if not a windows style option. Otherwise, sets opt name and value and returns true
+inline bool split_windows(const std::string &current, std::string &name, std::string &value) {
+    if(current.size() > 1 && current[0] == '/' && valid_first_char(current[1])) {
+        auto loc = current.find_first_of(':');
+        if(loc != std::string::npos) {
+            name = current.substr(1, loc - 1);
+            value = current.substr(loc + 1);
+        } else {
+            name = current.substr(1);
+            value = "";
+        }
+        return true;
+    } else
+        return false;
+}
+
 // Splits a string into multiple long and short names
 inline std::vector<std::string> split_names(std::string current) {
     std::vector<std::string> output;
diff --git a/include/CLI/StringTools.hpp b/include/CLI/StringTools.hpp
index 42e4ba10..f60cc3df 100644
--- a/include/CLI/StringTools.hpp
+++ b/include/CLI/StringTools.hpp
@@ -161,6 +161,16 @@ inline std::string find_and_replace(std::string str, std::string from, std::stri
     return str;
 }
 
+/// Find a trigger string and call a modify callable function that takes the current string and starting position of the
+/// trigger and returns the position in the string to search for the next trigger string
+template <typename Callable> inline std::string find_and_modify(std::string str, std::string trigger, Callable modify) {
+    size_t start_pos = 0;
+    while((start_pos = str.find(trigger, start_pos)) != std::string::npos) {
+        start_pos = modify(str, start_pos);
+    }
+    return str;
+}
+
 /// Split a string '"one two" "three"' into 'one two', 'three'
 /// Quote characters can be ` ' or "
 inline std::vector<std::string> split_up(std::string str) {
diff --git a/include/CLI/Validators.hpp b/include/CLI/Validators.hpp
index 91c5d9bc..25e67042 100644
--- a/include/CLI/Validators.hpp
+++ b/include/CLI/Validators.hpp
@@ -191,6 +191,33 @@ struct Range : public Validator {
     template <typename T> explicit Range(T max) : Range(static_cast<T>(0), max) {}
 };
 
+namespace detail {
+/// split a string into a program name and command line arguments
+/// the string is assumed to contain a file name followed by other arguments
+/// the return value contains is a pair with the first argument containing the program name and the second everything
+/// else
+inline std::pair<std::string, std::string> split_program_name(std::string commandline) {
+    // try to determine the programName
+    std::pair<std::string, std::string> vals;
+    trim(commandline);
+    auto esp = commandline.find_first_of(' ', 1);
+    while(!ExistingFile(commandline.substr(0, esp)).empty()) {
+        esp = commandline.find_first_of(' ', esp + 1);
+        if(esp == std::string::npos) {
+            // if we have reached the end and haven't found a valid file just assume the first argument is the
+            // program name
+            esp = commandline.find_first_of(' ', 1);
+            break;
+        }
+    }
+    vals.first = commandline.substr(0, esp);
+    rtrim(vals.first);
+    // strip the program name
+    vals.second = (esp != std::string::npos) ? commandline.substr(esp + 1) : std::string{};
+    ltrim(vals.second);
+    return vals;
+}
+} // namespace detail
 /// @}
 
 } // namespace CLI
diff --git a/tests/AppTest.cpp b/tests/AppTest.cpp
index af3a551a..a149509f 100644
--- a/tests/AppTest.cpp
+++ b/tests/AppTest.cpp
@@ -10,6 +10,15 @@ TEST_F(TApp, OneFlagShort) {
     EXPECT_EQ((size_t)1, app.count("--count"));
 }
 
+TEST_F(TApp, OneFlagShortWindows) {
+    app.add_flag("-c,--count");
+    args = {"/c"};
+    app.allow_windows_style_options();
+    run();
+    EXPECT_EQ((size_t)1, app.count("-c"));
+    EXPECT_EQ((size_t)1, app.count("--count"));
+}
+
 TEST_F(TApp, CountNonExist) {
     app.add_flag("-c,--count");
     args = {"-c"};
@@ -70,6 +79,17 @@ TEST_F(TApp, OneString) {
     EXPECT_EQ(str, "mystring");
 }
 
+TEST_F(TApp, OneStringWindowsStyle) {
+    std::string str;
+    app.add_option("-s,--string", str);
+    args = {"/string", "mystring"};
+    app.allow_windows_style_options();
+    run();
+    EXPECT_EQ((size_t)1, app.count("-s"));
+    EXPECT_EQ((size_t)1, app.count("--string"));
+    EXPECT_EQ(str, "mystring");
+}
+
 TEST_F(TApp, OneStringSingleStringInput) {
     std::string str;
     app.add_option("-s,--string", str);
@@ -90,6 +110,17 @@ TEST_F(TApp, OneStringEqualVersion) {
     EXPECT_EQ(str, "mystring");
 }
 
+TEST_F(TApp, OneStringEqualVersionWindowsStyle) {
+    std::string str;
+    app.add_option("-s,--string", str);
+    args = {"/string:mystring"};
+    app.allow_windows_style_options();
+    run();
+    EXPECT_EQ((size_t)1, app.count("-s"));
+    EXPECT_EQ((size_t)1, app.count("--string"));
+    EXPECT_EQ(str, "mystring");
+}
+
 TEST_F(TApp, OneStringEqualVersionSingleString) {
     std::string str;
     app.add_option("-s,--string", str);
@@ -119,6 +150,18 @@ TEST_F(TApp, OneStringEqualVersionSingleStringQuotedMultiple) {
     EXPECT_EQ(str3, "\"quoted string\"");
 }
 
+TEST_F(TApp, OneStringEqualVersionSingleStringQuotedMultipleMixedStyle) {
+    std::string str, str2, str3;
+    app.add_option("-s,--string", str);
+    app.add_option("-t,--tstr", str2);
+    app.add_option("-m,--mstr", str3);
+    app.allow_windows_style_options();
+    app.parse("/string:\"this is my quoted string\" /t 'qstring 2' -m=`\"quoted string\"`");
+    EXPECT_EQ(str, "this is my quoted string");
+    EXPECT_EQ(str2, "qstring 2");
+    EXPECT_EQ(str3, "\"quoted string\"");
+}
+
 TEST_F(TApp, OneStringEqualVersionSingleStringQuotedMultipleInMiddle) {
     std::string str, str2, str3;
     app.add_option("-s,--string", str);
@@ -1077,6 +1120,20 @@ TEST_F(TApp, InIntSet) {
     EXPECT_THROW(run(), CLI::ConversionError);
 }
 
+TEST_F(TApp, InIntSetWindows) {
+
+    int choice;
+    app.add_set("-q,--quick", choice, {1, 2, 3});
+    app.allow_windows_style_options();
+    args = {"/q", "2"};
+
+    run();
+    EXPECT_EQ(2, choice);
+
+    args = {"/q4"};
+    EXPECT_THROW(run(), CLI::ExtrasError);
+}
+
 TEST_F(TApp, FailSet) {
 
     int choice;
@@ -1547,14 +1604,28 @@ TEST_F(TApp, AllowExtrasOrder) {
 TEST_F(TApp, CheckShortFail) {
     args = {"--two"};
 
-    EXPECT_THROW(CLI::detail::AppFriend::parse_arg(&app, args, false), CLI::HorribleError);
+    EXPECT_THROW(CLI::detail::AppFriend::parse_arg(&app, args, CLI::detail::Classifier::SHORT), CLI::HorribleError);
 }
 
 // Test horrible error
 TEST_F(TApp, CheckLongFail) {
     args = {"-t"};
 
-    EXPECT_THROW(CLI::detail::AppFriend::parse_arg(&app, args, true), CLI::HorribleError);
+    EXPECT_THROW(CLI::detail::AppFriend::parse_arg(&app, args, CLI::detail::Classifier::LONG), CLI::HorribleError);
+}
+
+// Test horrible error
+TEST_F(TApp, CheckWindowsFail) {
+    args = {"-t"};
+
+    EXPECT_THROW(CLI::detail::AppFriend::parse_arg(&app, args, CLI::detail::Classifier::WINDOWS), CLI::HorribleError);
+}
+
+// Test horrible error
+TEST_F(TApp, CheckOtherFail) {
+    args = {"-t"};
+
+    EXPECT_THROW(CLI::detail::AppFriend::parse_arg(&app, args, CLI::detail::Classifier::NONE), CLI::HorribleError);
 }
 
 // Test horrible error
diff --git a/tests/CreationTest.cpp b/tests/CreationTest.cpp
index d8fa4dd7..0bd8a84d 100644
--- a/tests/CreationTest.cpp
+++ b/tests/CreationTest.cpp
@@ -471,6 +471,7 @@ TEST_F(TApp, SubcommandDefaults) {
     EXPECT_FALSE(app.get_prefix_command());
     EXPECT_FALSE(app.get_ignore_case());
     EXPECT_FALSE(app.get_ignore_underscore());
+    EXPECT_FALSE(app.get_allow_windows_style_options());
     EXPECT_FALSE(app.get_fallthrough());
     EXPECT_EQ(app.get_footer(), "");
     EXPECT_EQ(app.get_group(), "Subcommands");
@@ -481,6 +482,7 @@ TEST_F(TApp, SubcommandDefaults) {
     app.prefix_command();
     app.ignore_case();
     app.ignore_underscore();
+    app.allow_windows_style_options();
     app.fallthrough();
     app.footer("footy");
     app.group("Stuff");
@@ -493,6 +495,7 @@ TEST_F(TApp, SubcommandDefaults) {
     EXPECT_TRUE(app2->get_prefix_command());
     EXPECT_TRUE(app2->get_ignore_case());
     EXPECT_TRUE(app2->get_ignore_underscore());
+    EXPECT_TRUE(app2->get_allow_windows_style_options());
     EXPECT_TRUE(app2->get_fallthrough());
     EXPECT_EQ(app2->get_footer(), "footy");
     EXPECT_EQ(app2->get_group(), "Stuff");
diff --git a/tests/HelpersTest.cpp b/tests/HelpersTest.cpp
index 2b6cb976..174272ce 100644
--- a/tests/HelpersTest.cpp
+++ b/tests/HelpersTest.cpp
@@ -32,6 +32,42 @@ TEST(String, InvalidName) {
     EXPECT_TRUE(CLI::detail::valid_name_string("va-li-d"));
     EXPECT_FALSE(CLI::detail::valid_name_string("vali&d"));
     EXPECT_TRUE(CLI::detail::valid_name_string("_valid"));
+    EXPECT_FALSE(CLI::detail::valid_name_string("/valid"));
+}
+
+TEST(StringTools, Modify) {
+    int cnt = 0;
+    std::string newString = CLI::detail::find_and_modify("======", "=", [&cnt](std::string &str, size_t index) {
+        if((++cnt) % 2 == 0) {
+            str[index] = ':';
+        }
+        return index + 1;
+    });
+    EXPECT_EQ(newString, "=:=:=:");
+}
+
+TEST(StringTools, Modify2) {
+    int cnt = 0;
+    std::string newString =
+        CLI::detail::find_and_modify("this is a string test", "is", [&cnt](std::string &str, size_t index) {
+            if((index > 1) && (str[index - 1] != ' ')) {
+                str[index] = 'a';
+                str[index + 1] = 't';
+            }
+            return index + 1;
+        });
+    EXPECT_EQ(newString, "that is a string test");
+}
+
+TEST(StringTools, Modify3) {
+    int cnt = 0;
+    // this picks up 3 sets of 3 after the 'b' then collapses the new first set
+    std::string newString = CLI::detail::find_and_modify("baaaaaaaaaa", "aaa", [&cnt](std::string &str, size_t index) {
+        str.erase(index, 3);
+        str.insert(str.begin(), 'a');
+        return 0;
+    });
+    EXPECT_EQ(newString, "aba");
 }
 
 TEST(Trim, Various) {
@@ -212,6 +248,36 @@ TEST(Validators, CombinedPaths) {
     EXPECT_FALSE(CLI::ExistingFile(myfile).empty());
 }
 
+TEST(Validators, ProgramNameSplit) {
+    TempFile myfile{"program_name1.exe"};
+    {
+        std::ofstream out{myfile};
+        out << "useless string doesn't matter" << std::endl;
+    }
+    auto res =
+        CLI::detail::split_program_name(std::string("./") + std::string(myfile) + " this is a bunch of extra stuff  ");
+    EXPECT_EQ(res.first, std::string("./") + std::string(myfile));
+    EXPECT_EQ(res.second, "this is a bunch of extra stuff");
+
+    TempFile myfile2{"program name1.exe"};
+    {
+        std::ofstream out{myfile2};
+        out << "useless string doesn't matter" << std::endl;
+    }
+    res = CLI::detail::split_program_name(std::string("   ") + std::string("./") + std::string(myfile2) +
+                                          "      this is a bunch of extra stuff  ");
+    EXPECT_EQ(res.first, std::string("./") + std::string(myfile2));
+    EXPECT_EQ(res.second, "this is a bunch of extra stuff");
+
+    res = CLI::detail::split_program_name("./program_name    this is a bunch of extra stuff  ");
+    EXPECT_EQ(res.first, "./program_name"); // test sectioning of first argument even if it can't detect the file
+    EXPECT_EQ(res.second, "this is a bunch of extra stuff");
+
+    res = CLI::detail::split_program_name(std::string("  ./") + std::string(myfile) + "    ");
+    EXPECT_EQ(res.first, std::string("./") + std::string(myfile));
+    EXPECT_TRUE(res.second.empty());
+}
+
 // Yes, this is testing an app_helper :)
 TEST(AppHelper, TempfileCreated) {
     std::string name = "TestFileNotUsed.txt";
diff --git a/tests/StringParseTest.cpp b/tests/StringParseTest.cpp
index a457403c..b37ad162 100644
--- a/tests/StringParseTest.cpp
+++ b/tests/StringParseTest.cpp
@@ -26,30 +26,6 @@ TEST_F(TApp, ExistingExeCheck) {
     EXPECT_EQ(str3, "\"quoted string\"");
 }
 
-TEST_F(TApp, ExistingExeCheckWithSpace) {
-
-    TempFile tmpexe{"Space File.out"};
-
-    std::string str, str2, str3;
-    app.add_option("-s,--string", str);
-    app.add_option("-t,--tstr", str2);
-    app.add_option("-m,--mstr", str3);
-
-    {
-        std::ofstream out{tmpexe};
-        out << "useless string doesn't matter" << std::endl;
-    }
-
-    app.parse(std::string("./") + std::string(tmpexe) +
-                  " --string=\"this is my quoted string\" -t 'qstring 2' -m=`\"quoted string\"`",
-              true);
-    EXPECT_EQ(str, "this is my quoted string");
-    EXPECT_EQ(str2, "qstring 2");
-    EXPECT_EQ(str3, "\"quoted string\"");
-
-    EXPECT_EQ(app.get_name(), std::string("./") + std::string(tmpexe));
-}
-
 TEST_F(TApp, ExistingExeCheckWithLotsOfSpace) {
 
     TempFile tmpexe{"this is a weird file.exe"};