diff --git a/components/servo/Cargo.lock b/components/servo/Cargo.lock
index 620ec07eb28..d09f61f623e 100644
--- a/components/servo/Cargo.lock
+++ b/components/servo/Cargo.lock
@@ -2071,6 +2071,7 @@ dependencies = [
  "euclid 0.6.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "plugins 0.0.1",
+ "rustc-serialize 0.3.19 (registry+https://github.com/rust-lang/crates.io-index)",
  "selectors 0.5.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "string_cache 0.2.12 (registry+https://github.com/rust-lang/crates.io-index)",
  "style 0.0.1",
diff --git a/python/servo/testing_commands.py b/python/servo/testing_commands.py
index f0eccee59af..ee6fbd05837 100644
--- a/python/servo/testing_commands.py
+++ b/python/servo/testing_commands.py
@@ -14,8 +14,6 @@ import re
 import sys
 import os
 import os.path as path
-import subprocess
-import json
 from collections import OrderedDict
 from time import time
 
@@ -141,8 +139,6 @@ class MachCommands(CommandBase):
     @CommandArgument('test_name', nargs=argparse.REMAINDER,
                      help="Only run tests that match this pattern or file path")
     def test_unit(self, test_name=None, package=None):
-        check_css_properties_json(self.context.topdir)
-
         if test_name is None:
             test_name = []
 
@@ -657,23 +653,3 @@ testing/web-platform/mozilla/tests for Servo-only tests""" % reference_path)
 
         if editor:
             proc.wait()
-
-
-def check_css_properties_json(topdir):
-    print("Testing generation of css-properties.json...")
-    filename = path.join(topdir, "target", "doc", "servo", "css-properties.json")
-
-    if path.exists(filename):
-        os.remove(filename)
-    subprocess.check_call([
-        sys.executable,
-        path.join(topdir, "components", "style", "properties", "build.py"),
-        "servo",
-        "html",
-    ])
-    properties = json.load(open(filename))
-
-    assert len(properties) >= 100
-    assert "margin-top" in properties
-    assert "margin" in properties
-    print("OK")
diff --git a/tests/unit/style/Cargo.toml b/tests/unit/style/Cargo.toml
index 0b6ffdf843b..24bb07c95b7 100644
--- a/tests/unit/style/Cargo.toml
+++ b/tests/unit/style/Cargo.toml
@@ -30,3 +30,4 @@ euclid = {version = "0.6.4", features = ["plugins"]}
 selectors = {version = "0.5", features = ["heap_size"]}
 string_cache = {version = "0.2.12", features = ["heap_size"]}
 url = {version = "1.0.0", features = ["heap_size"]}
+rustc-serialize = "0.3"
diff --git a/tests/unit/style/lib.rs b/tests/unit/style/lib.rs
index 9869ff4af72..7f6a1c11b7f 100644
--- a/tests/unit/style/lib.rs
+++ b/tests/unit/style/lib.rs
@@ -10,6 +10,7 @@ extern crate app_units;
 extern crate cssparser;
 extern crate euclid;
 extern crate msg;
+extern crate rustc_serialize;
 extern crate selectors;
 #[macro_use(atom, ns)] extern crate string_cache;
 extern crate style;
@@ -20,6 +21,7 @@ extern crate util;
 #[cfg(test)] mod attr;
 #[cfg(test)] mod logical_geometry;
 #[cfg(test)] mod media_queries;
+#[cfg(test)] mod properties;
 #[cfg(test)] mod stylesheets;
 #[cfg(test)] mod viewport;
 
diff --git a/tests/unit/style/properties.rs b/tests/unit/style/properties.rs
new file mode 100644
index 00000000000..9f4c3f08af0
--- /dev/null
+++ b/tests/unit/style/properties.rs
@@ -0,0 +1,53 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use rustc_serialize::json::Json;
+use std::env;
+use std::fs::{File, remove_file};
+use std::path::Path;
+use std::process::Command;
+
+#[test]
+fn properties_list_json() {
+    let top = Path::new(file!()).parent().unwrap().join("..").join("..").join("..");
+    let json = top.join("target").join("doc").join("servo").join("css-properties.json");
+    if json.exists() {
+        remove_file(&json).unwrap()
+    }
+    let python = env::var("PYTHON").ok().unwrap_or_else(find_python);
+    let script = top.join("components").join("style").join("properties").join("build.py");
+    let status = Command::new(python)
+        .arg(&script)
+        .arg("servo")
+        .arg("html")
+        .status()
+        .unwrap();
+    assert!(status.success());
+    let properties = Json::from_reader(&mut File::open(json).unwrap()).unwrap();
+    assert!(properties.as_object().unwrap().len() > 100);
+    assert!(properties.find("margin").is_some());
+    assert!(properties.find("margin-top").is_some());
+}
+
+#[cfg(windows)]
+fn find_python() -> String {
+    if Command::new("python27.exe").arg("--version").output().is_ok() {
+        return "python27.exe".to_owned();
+    }
+
+    if Command::new("python.exe").arg("--version").output().is_ok() {
+        return "python.exe".to_owned();
+    }
+
+    panic!("Can't find python (tried python27.exe and python.exe)! Try fixing PATH or setting the PYTHON env var");
+}
+
+#[cfg(not(windows))]
+fn find_python() -> String {
+    if Command::new("python2.7").arg("--version").output().unwrap().status.success() {
+        "python2.7"
+    } else {
+        "python"
+    }.to_owned()
+}