diff --git a/README.md b/README.md
index ac193186300..0c83a837d29 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ For more detailed build instructions, see the Servo book under [Setting up your
 
 ### macOS
 
-- Download and install [`python`](https://www.python.org/downloads/macos/), [Xcode](https://developer.apple.com/xcode/), and [`brew`](https://brew.sh/)
+- Download and install [`python`](https://www.python.org/downloads/macos/) (version 3.10 to 3.12), [Xcode](https://developer.apple.com/xcode/), and [`brew`](https://brew.sh/).
 - Install `rustup`: `curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh`
 - Restart your shell to make sure `cargo` is available
 - Install the other dependencies: `./mach bootstrap`
@@ -25,7 +25,7 @@ For more detailed build instructions, see the Servo book under [Setting up your
 
 ### Linux
 
-- Install `curl` and `python`:
+- Install `curl` and `python` (version 3.10 to 3.12):
   - Arch: `sudo pacman -S --needed curl python python-pip`
   - Debian, Ubuntu: `sudo apt install curl python3-pip python3-venv python3-setuptools`
   - Fedora: `sudo dnf install curl python3 python3-pip python3-devel`
@@ -37,7 +37,7 @@ For more detailed build instructions, see the Servo book under [Setting up your
 
 ### Windows
 
-- Download and install [`python`](https://www.python.org/downloads/windows/), [`choco`](https://chocolatey.org/install#individual), and [`rustup`](https://win.rustup.rs/)
+- Download and install [`python`](https://www.python.org/downloads/windows/) (version 3.10 to 3.12), [`choco`](https://chocolatey.org/install#individual), and [`rustup`](https://win.rustup.rs/)
   - Be sure to select *Quick install via the Visual Studio Community installer*
 - In the Visual Studio Installer, ensure the following components are installed:
   - **Windows 10 SDK (10.0.19041.0)** (`Microsoft.VisualStudio.Component.Windows10SDK.19041`)
diff --git a/mach b/mach
index 67d2d45e3d5..2ff80f6b51d 100755
--- a/mach
+++ b/mach
@@ -12,11 +12,15 @@
 import os
 import sys
 
-if sys.version_info < (3, 10):
-    print("mach does not support python < 3.10, please install python 3 >= 3.10")
+# Destructure because version_info > max_ver is true when running the same version.
+ver = (sys.version_info[0], sys.version_info[1])
+min_ver = (3, 10)
+max_ver = (3, 12) # WPT does not support Python 3.13. See issue #34095.
+if ver < min_ver or ver > max_ver:
+    print("mach does not support python {0}.{1}, please install 3.{2} <= python <= 3.{3}" \
+        .format(ver[0], ver[1], min_ver[1], max_ver[1]))
     sys.exit(1)
 
-
 def main(args):
     topdir = os.path.abspath(os.path.dirname(sys.argv[0]))
     sys.path.insert(0, os.path.join(topdir, "python"))