diff --git a/.github/scripts/install-arduino-ide.sh b/.github/scripts/install-arduino-ide.sh
index 7e268b1..ce60cb8 100755
--- a/.github/scripts/install-arduino-ide.sh
+++ b/.github/scripts/install-arduino-ide.sh
@@ -75,16 +75,17 @@ if [ ! -d "$ARDUINO_IDE_PATH" ]; then
 	echo ""
 fi
 
-function build_sketch(){ # build_sketch <fqbn> <path-to-ino> [extra-options]
+function build_sketch(){ # build_sketch <fqbn> <path-to-ino> <build-flags> [extra-options]
     if [ "$#" -lt 2 ]; then
 		echo "ERROR: Illegal number of parameters"
-		echo "USAGE: build_sketch <fqbn> <path-to-ino> [extra-options]"
+		echo "USAGE: build_sketch <fqbn> <path-to-ino> <build-flags> [extra-options]"
 		return 1
 	fi
 
 	local fqbn="$1"
 	local sketch="$2"
-	local xtra_opts="$3"
+    local build_flags="$3"
+    local xtra_opts="$4"
 	local win_opts=""
 	if [ "$OS_IS_WINDOWS" == "1" ]; then
 		local ctags_version=`ls "$ARDUINO_IDE_PATH/tools-builder/ctags/"`
@@ -107,6 +108,7 @@ function build_sketch(){ # build_sketch <fqbn> <path-to-ino> [extra-options]
 		-libraries "$ARDUINO_USR_PATH/libraries" \
 		-build-cache "$ARDUINO_CACHE_DIR" \
 		-build-path "$ARDUINO_BUILD_DIR" \
+        -prefs=compiler.cpp.extra_flags="$build_flags" \
 		$win_opts $xtra_opts "$sketch"
 }
 
@@ -210,7 +212,13 @@ function build_sketches() # build_sketches <fqbn> <examples-path> <chunk> <total
         || [ "$sketchnum" -gt "$end_index" ]; then
         	continue
         fi
-        build_sketch "$fqbn" "$sketch" "$xtra_opts"
+        local sketchBuildFlags=""
+        if [ -f "$sketchdir/.test.build_flags" ]; then
+            while read line; do
+                sketchBuildFlags="$sketchBuildFlags $line"
+            done < "$sketchdir/.test.build_flags"
+        fi
+        build_sketch "$fqbn" "$sketch" "$sketchBuildFlags" "$xtra_opts"
         local result=$?
         if [ $result -ne 0 ]; then
             return $result
diff --git a/.github/scripts/install-platformio.sh b/.github/scripts/install-platformio.sh
index 61c94fe..594948e 100644
--- a/.github/scripts/install-platformio.sh
+++ b/.github/scripts/install-platformio.sh
@@ -10,19 +10,20 @@ echo "PlatformIO has been installed"
 echo ""
 
 
-function build_pio_sketch(){ # build_pio_sketch <board> <path-to-ino>
-    if [ "$#" -lt 2 ]; then
+function build_pio_sketch(){ # build_pio_sketch <board> <path-to-ino> <build-flags>
+    if [ "$#" -lt 3 ]; then
         echo "ERROR: Illegal number of parameters"
-        echo "USAGE: build_pio_sketch <board> <path-to-ino>"
+        echo "USAGE: build_pio_sketch <board> <path-to-ino> <build-flags>"
         return 1
     fi
 
 	local board="$1"
 	local sketch="$2"
+    local buildFlags="$3"
 	local sketch_dir=$(dirname "$sketch")
 	echo ""
 	echo "Compiling '"$(basename "$sketch")"' ..."
-	python -m platformio ci -l '.' --board "$board" "$sketch_dir" --project-option="board_build.partitions = huge_app.csv"
+	python -m platformio ci -l '.' --board "$board" "$sketch_dir" --project-option="board_build.partitions = huge_app.csv" --project-option="build_flags=$buildFlags"
 }
 
 function count_sketches() # count_sketches <examples-path>
@@ -118,12 +119,18 @@ function build_pio_sketches() # build_pio_sketches <board> <examples-path> <chun
         || [ -f "$sketchdir/.test.skip" ]; then
             continue
         fi
+        local sketchBuildFlags=""
+        if [ -f "$sketchdir/.test.build_flags" ]; then
+            while read line; do
+                sketchBuildFlags="$sketchBuildFlags $line"
+            done < "$sketchdir/.test.build_flags"
+        fi
         sketchnum=$(($sketchnum + 1))
         if [ "$sketchnum" -le "$start_index" ] \
         || [ "$sketchnum" -gt "$end_index" ]; then
         	continue
         fi
-        build_pio_sketch "$board" "$sketch"
+        build_pio_sketch "$board" "$sketch" "$sketchBuildFlags"
         local result=$?
         if [ $result -ne 0 ]; then
             return $result
diff --git a/README.md b/README.md
index c1992a9..d6dd320 100644
--- a/README.md
+++ b/README.md
@@ -89,6 +89,7 @@ To use this library you might need to have the latest git versions of [ESP32](ht
     - [Setup global and class functions as request handlers](#setup-global-and-class-functions-as-request-handlers)
     - [Methods for controlling websocket connections](#methods-for-controlling-websocket-connections)
     - [Adding Default Headers](#adding-default-headers)
+    - [Path variable](#path-variable)
 
 ## Installation
 
@@ -1484,3 +1485,37 @@ webServer.onNotFound([](AsyncWebServerRequest *request) {
   }
 });
 ```
+
+### Path variable
+
+With path variable you can create a custom regex rule for a specific parameter in a route. 
+For example we want a `sensorId` parameter in a route rule to match only a integer.
+
+```cpp
+  server.on("^\\/sensor\\/([0-9]+)$", HTTP_GET, [] (AsyncWebServerRequest *request) {
+      String sensorId = request->pathArg(0);
+  });
+```
+*NOTE*: All regex patterns starts with `^` and ends with `$`
+
+To enable the `Path variable` support, you have to define the buildflag `-DASYNCWEBSERVER_REGEX`.
+
+
+For Arduino IDE create/update `platform.local.txt`:
+
+`Windows`: C:\Users\(username)\AppData\Local\Arduino15\packages\\`{espxxxx}`\hardware\\`espxxxx`\\`{version}`\platform.local.txt
+
+`Linux`: ~/.arduino15/packages/`{espxxxx}`/hardware/`{espxxxx}`/`{version}`/platform.local.txt
+
+Add/Update the following line:
+```
+  compiler.cpp.extra_flags=-DDASYNCWEBSERVER_REGEX
+```
+
+For platformio modify `platformio.ini`:
+```ini
+[env:myboard]
+build_flags = 
+  -DASYNCWEBSERVER_REGEX
+```
+*NOTE*: By enabling `ASYNCWEBSERVER_REGEX`, `<regex>` will be included. This will add an 100k to your binary.
diff --git a/examples/regex_patterns/.test.build_flags b/examples/regex_patterns/.test.build_flags
new file mode 100644
index 0000000..9ea3bb7
--- /dev/null
+++ b/examples/regex_patterns/.test.build_flags
@@ -0,0 +1 @@
+-DASYNCWEBSERVER_REGEX=1
diff --git a/examples/regex_patterns/regex_patterns.ino b/examples/regex_patterns/regex_patterns.ino
index 4ec9c85..fb01306 100644
--- a/examples/regex_patterns/regex_patterns.ino
+++ b/examples/regex_patterns/regex_patterns.ino
@@ -5,6 +5,18 @@
 //  * handle missing pages / 404s
 //
 
+// Add buildflag ASYNCWEBSERVER_REGEX to enable the regex support
+
+// For platformio: platformio.ini:
+//  build_flags = 
+//      -DASYNCWEBSERVER_REGEX
+
+// For arduino IDE: create/update platform.local.txt
+// Windows: C:\Users\(username)\AppData\Local\Arduino15\packages\espxxxx\hardware\espxxxx\{version}\platform.local.txt
+// Linux: ~/.arduino15/packages/espxxxx/hardware/espxxxx/{version}/platform.local.txt
+//
+// compiler.cpp.extra_flags=-DASYNCWEBSERVER_REGEX=1
+
 #include <Arduino.h>
 #ifdef ESP32
 #include <WiFi.h>
diff --git a/src/ESPAsyncWebServer.h b/src/ESPAsyncWebServer.h
index 4f0574a..7cd21aa 100644
--- a/src/ESPAsyncWebServer.h
+++ b/src/ESPAsyncWebServer.h
@@ -38,6 +38,12 @@
 #error Platform not supported
 #endif
 
+#ifdef ASYNCWEBSERVER_REGEX
+#define ASYNCWEBSERVER_REGEX_ATTRIBUTE
+#else
+#define ASYNCWEBSERVER_REGEX_ATTRIBUTE __attribute__((warning("ASYNCWEBSERVER_REGEX not defined")))
+#endif
+
 #define DEBUGF(...) //Serial.printf(__VA_ARGS__)
 
 class AsyncWebServer;
@@ -271,7 +277,7 @@ class AsyncWebServerRequest {
     bool hasArg(const char* name) const;         // check if argument exists
     bool hasArg(const __FlashStringHelper * data) const;         // check if F(argument) exists
 
-    const String& pathArg(size_t i) const;
+    const String& ASYNCWEBSERVER_REGEX_ATTRIBUTE pathArg(size_t i) const;
 
     const String& header(const char* name) const;// get request header value by name
     const String& header(const __FlashStringHelper * data) const;// get request header value by F(name)    
diff --git a/src/WebHandlerImpl.h b/src/WebHandlerImpl.h
index 5ae7b49..d121fa7 100644
--- a/src/WebHandlerImpl.h
+++ b/src/WebHandlerImpl.h
@@ -22,7 +22,9 @@
 #define ASYNCWEBSERVERHANDLERIMPL_H_
 
 #include <string>
+#ifdef ASYNCWEBSERVER_REGEX
 #include <regex>
+#endif
 
 #include "stddef.h"
 #include <time.h>
@@ -71,10 +73,10 @@ class AsyncCallbackWebHandler: public AsyncWebHandler {
     ArBodyHandlerFunction _onBody;
     bool _isRegex;
   public:
-    AsyncCallbackWebHandler() : _uri(), _method(HTTP_ANY), _onRequest(NULL), _onUpload(NULL), _onBody(NULL), _isRegex(false){}
+    AsyncCallbackWebHandler() : _uri(), _method(HTTP_ANY), _onRequest(NULL), _onUpload(NULL), _onBody(NULL), _isRegex(false) {}
     void setUri(const String& uri){ 
       _uri = uri; 
-       _isRegex = uri.startsWith("^") && uri.endsWith("$");
+      _isRegex = uri.startsWith("^") && uri.endsWith("$");
     }
     void setMethod(WebRequestMethodComposite method){ _method = method; }
     void onRequest(ArRequestHandlerFunction fn){ _onRequest = fn; }
@@ -89,18 +91,21 @@ class AsyncCallbackWebHandler: public AsyncWebHandler {
       if(!(_method & request->method()))
         return false;
 
+#ifdef ASYNCWEBSERVER_REGEX
       if (_isRegex) {
-        std::regex rgx(_uri.c_str());
+        std::regex pattern(_uri.c_str());
         std::smatch matches;
         std::string s(request->url().c_str());
-        if(std::regex_search(s, matches, rgx)) {
+        if(std::regex_search(s, matches, pattern)) {
           for (size_t i = 1; i < matches.size(); ++i) { // start from 1
             request->_addPathParam(matches[i].str().c_str());
           }
         } else {
           return false;
         }
-      } else if (_uri.length() && _uri.endsWith("*")) {
+      } else 
+#endif
+      if (_uri.length() && _uri.endsWith("*")) {
         String uriTemplate = String(_uri);
 	uriTemplate = uriTemplate.substring(0, uriTemplate.length() - 1);
         if (!request->url().startsWith(uriTemplate))