diff --git a/.clang-tidy b/.clang-tidy
index 3acf30c3..a1a36f5f 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -1,6 +1,6 @@
 #Checks: '*,-clang-analyzer-alpha.*'
 #Checks: '-*,google-readability-casting,llvm-namespace-comment,performance-unnecessary-value-param,llvm-include-order,misc-throw-by-value-catch-by-reference,readability-container-size-empty,google-runtime-references,modernize*'
-Checks: '-*,llvm-namespace-comment'
+Checks: '-*,llvm-namespace-comment,llvm-include-order'
 HeaderFilterRegex: '.*hpp'
 CheckOptions:
 - key:             readability-braces-around-statements.ShortStatementLines
diff --git a/include/CLI/App.hpp b/include/CLI/App.hpp
index 645b7e4c..cc00f4dd 100644
--- a/include/CLI/App.hpp
+++ b/include/CLI/App.hpp
@@ -3,26 +3,26 @@
 // Distributed under the LGPL v2.1 license.  See accompanying
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
-#include <string>
-#include <memory>
-#include <deque>
-#include <iostream>
-#include <functional>
 #include <algorithm>
-#include <sstream>
-#include <set>
+#include <deque>
+#include <functional>
+#include <iostream>
+#include <memory>
 #include <numeric>
+#include <set>
+#include <sstream>
+#include <string>
 #include <utility>
 #include <vector>
 
 
 // CLI Library includes
 #include "CLI/Error.hpp"
-#include "CLI/TypeTools.hpp"
-#include "CLI/StringTools.hpp"
-#include "CLI/Split.hpp"
-#include "CLI/Option.hpp"
 #include "CLI/Ini.hpp"
+#include "CLI/Option.hpp"
+#include "CLI/Split.hpp"
+#include "CLI/StringTools.hpp"
+#include "CLI/TypeTools.hpp"
 
 namespace CLI {
 
diff --git a/include/CLI/CLI.hpp b/include/CLI/CLI.hpp
index dbf36132..2beaa5f0 100644
--- a/include/CLI/CLI.hpp
+++ b/include/CLI/CLI.hpp
@@ -4,12 +4,12 @@
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
 // CLI Library includes
-#include "CLI/Error.hpp"
-#include "CLI/TypeTools.hpp"
-#include "CLI/StringTools.hpp"
-#include "CLI/Ini.hpp"
-#include "CLI/Split.hpp"
-#include "CLI/Validators.hpp"
-#include "CLI/Option.hpp"
 #include "CLI/App.hpp"
+#include "CLI/Error.hpp"
+#include "CLI/Ini.hpp"
+#include "CLI/Option.hpp"
+#include "CLI/Split.hpp"
+#include "CLI/StringTools.hpp"
+#include "CLI/TypeTools.hpp"
+#include "CLI/Validators.hpp"
 
diff --git a/include/CLI/Error.hpp b/include/CLI/Error.hpp
index 897e53c1..27fdbd5b 100644
--- a/include/CLI/Error.hpp
+++ b/include/CLI/Error.hpp
@@ -3,9 +3,9 @@
 // Distributed under the LGPL v2.1 license.  See accompanying
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
-#include <string>
 #include <exception>
 #include <stdexcept>
+#include <string>
 
 namespace CLI {
 
diff --git a/include/CLI/Ini.hpp b/include/CLI/Ini.hpp
index e3c32085..f84f2a6b 100644
--- a/include/CLI/Ini.hpp
+++ b/include/CLI/Ini.hpp
@@ -3,10 +3,10 @@
 // Distributed under the LGPL v2.1 license.  See accompanying
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
-#include <fstream>
-#include <string>
-#include <iostream>
 #include <algorithm>
+#include <fstream>
+#include <iostream>
+#include <string>
 
 #include "CLI/StringTools.hpp"
 
diff --git a/include/CLI/Option.hpp b/include/CLI/Option.hpp
index 0b63300b..0f4c2421 100644
--- a/include/CLI/Option.hpp
+++ b/include/CLI/Option.hpp
@@ -3,18 +3,18 @@
 // Distributed under the LGPL v2.1 license.  See accompanying
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
-#include <string>
-#include <functional>
-#include <utility>
-#include <vector>
-#include <tuple>
 #include <algorithm>
+#include <functional>
 #include <memory>
 #include <set>
+#include <string>
+#include <tuple>
+#include <utility>
+#include <vector>
 
 #include "CLI/Error.hpp"
-#include "CLI/StringTools.hpp"
 #include "CLI/Split.hpp"
+#include "CLI/StringTools.hpp"
 
 namespace CLI {
 
diff --git a/include/CLI/Split.hpp b/include/CLI/Split.hpp
index d461ca95..befb0de5 100644
--- a/include/CLI/Split.hpp
+++ b/include/CLI/Split.hpp
@@ -4,8 +4,8 @@
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
 #include <string>
-#include <vector>
 #include <tuple>
+#include <vector>
 
 #include "CLI/Error.hpp"
 #include "CLI/StringTools.hpp"
diff --git a/include/CLI/StringTools.hpp b/include/CLI/StringTools.hpp
index db86ac5c..8d4534a6 100644
--- a/include/CLI/StringTools.hpp
+++ b/include/CLI/StringTools.hpp
@@ -3,12 +3,12 @@
 // Distributed under the LGPL v2.1 license.  See accompanying
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
-#include <string>
-#include <sstream>
+#include <algorithm>
 #include <iomanip>
 #include <locale>
+#include <sstream>
+#include <string>
 #include <type_traits>
-#include <algorithm>
 
 namespace CLI {
 namespace detail {
diff --git a/include/CLI/Timer.hpp b/include/CLI/Timer.hpp
index 60a3e002..97ad23b0 100644
--- a/include/CLI/Timer.hpp
+++ b/include/CLI/Timer.hpp
@@ -3,10 +3,10 @@
 // Distributed under the LGPL v2.1 license.  See accompanying
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
-#include <string>
-#include <iostream>
 #include <chrono>
 #include <functional>
+#include <iostream>
+#include <string>
 #include <utility>
 
 namespace CLI {
diff --git a/include/CLI/TypeTools.hpp b/include/CLI/TypeTools.hpp
index c1dab70f..7fd11314 100644
--- a/include/CLI/TypeTools.hpp
+++ b/include/CLI/TypeTools.hpp
@@ -3,10 +3,10 @@
 // Distributed under the LGPL v2.1 license.  See accompanying
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
-#include <vector>
-#include <type_traits>
-#include <string>
 #include <exception>
+#include <string>
+#include <type_traits>
+#include <vector>
 
 namespace CLI {
 
diff --git a/include/CLI/Validators.hpp b/include/CLI/Validators.hpp
index 82b1e9c2..e1b16334 100644
--- a/include/CLI/Validators.hpp
+++ b/include/CLI/Validators.hpp
@@ -3,16 +3,16 @@
 // Distributed under the LGPL v2.1 license.  See accompanying
 // file LICENSE or https://github.com/CLIUtils/CLI11 for details.
 
-#include <string>
-#include <iostream>
-#include <functional>
 #include "CLI/TypeTools.hpp"
+#include <functional>
+#include <iostream>
+#include <string>
 
 // C standard library
 // Only needed for existence checking
 // Could be swapped for filesystem in C++17
-#include <sys/types.h>
 #include <sys/stat.h>
+#include <sys/types.h>
 
 namespace CLI {