diff --git a/README.md b/README.md
index a445cc84..652c13ec 100644
--- a/README.md
+++ b/README.md
@@ -112,6 +112,7 @@ As of Eel v0.12.0, the following options are available to `start()`:
  - **block**, a bool saying whether or not the call to `start()` should block the calling thread. *Default: `True`*
  - **jinja_templates**, a string specifying a folder to use for Jinja2 templates, e.g. `my_templates`. *Default:  `None`*
  - **cmdline_args**, a list of strings to pass to the command to start the browser. For example, we might add extra flags for Chrome; ```eel.start('main.html', mode='chrome-app', port=8080, cmdline_args=['--start-fullscreen', '--browser-startup-dialog'])```. *Default: `[]`*
+ - **custom_callback**, a callback function to be called when using `"custom"` mode which would be responsible for calling `subprocess.Popen` for example. It receives an array of command line arguments and an array of start urls in argument: `custom_callback(args, urls)`. If not set, the `cmdline_args` option is launched as the command to execute.
  - **size**, a tuple of ints specifying the (width, height) of the main window in pixels *Default: `None`*
  - **position**, a tuple of ints specifying the (left, top) of the main window in pixels *Default: `None`*
  - **geometry**, a dictionary specifying the size and position for all windows. The keys should be the relative path of the page, and the values should be a dictionary of the form `{'size': (200, 100), 'position': (300, 50)}`. *Default: {}*
diff --git a/eel/__init__.py b/eel/__init__.py
index 2f28ce89..059dc7f9 100644
--- a/eel/__init__.py
+++ b/eel/__init__.py
@@ -294,9 +294,11 @@ def _process_message(message, ws):
 
 
 def _get_real_path(path):
-    if getattr(sys, 'frozen', False):
+    if getattr(sys, 'frozen', False) and hasattr(sys, "_MEIPASS"):
+        # Pyinstaller uses _MEIPASS for frozen paths
         return os.path.join(sys._MEIPASS, path)
     else:
+        # Unfrozen app or cx_freeze can use the path directly
         return os.path.abspath(path)
 
 
diff --git a/eel/browsers.py b/eel/browsers.py
index 79639141..872e67db 100644
--- a/eel/browsers.py
+++ b/eel/browsers.py
@@ -48,8 +48,11 @@ def open(start_pages, options):
         pass
     elif mode == 'custom':
         # Just run whatever command the user provided
-        sps.Popen(options['cmdline_args'],
-                  stdout=sps.PIPE, stderr=sps.PIPE, stdin=sps.PIPE)
+        if options["custom_callback"]:
+            options["custom_callback"](options['cmdline_args'], start_urls)
+        else:
+            sps.Popen(options['cmdline_args'],
+                      stdout=sps.PIPE, stderr=sps.PIPE, stdin=sps.PIPE)
     elif mode in _browser_modules:
         # Run with a specific browser
         browser_module = _browser_modules[mode]
diff --git a/eel/electron.py b/eel/electron.py
index 7a443025..80fc3300 100644
--- a/eel/electron.py
+++ b/eel/electron.py
@@ -15,7 +15,13 @@ def find_path():
     if sys.platform in ['win32', 'win64']:
         # It doesn't work well passing the .bat file to Popen, so we get the actual .exe
         bat_path = wch.which('electron')
-        return os.path.join(bat_path, r'..\node_modules\electron\dist\electron.exe')
+        if bat_path is not None:
+            exe_path = os.path.join(bat_path, r'..\node_modules\electron\dist\electron.exe')
+            if os.path.exists(exe_path):
+                return exe_path
+            else:
+                return bat_path
+        return None
     elif sys.platform in ['darwin', 'linux']:
         # This should work find...
         return wch.which('electron')