diff --git a/plug/pip_resolve.py b/plug/pip_resolve.py
index 60796480..20a7555c 100644
--- a/plug/pip_resolve.py
+++ b/plug/pip_resolve.py
@@ -6,6 +6,7 @@
 import pip
 import pkg_resources
 import utils
+import re
 
 
 def create_tree_of_packages_dependencies(dist_tree, packages_names, req_file_path):
@@ -63,8 +64,24 @@ def create_package_as_root(package, dir_as_root):
         dir_as_root[DEPENDENCIES][package_as_root[NAME]] = package_tree
     return dir_as_root
 
+sys_platform_re = re.compile('sys_platform\s*==\s*[\'"](.+)[\'"]')
+sys_platform = sys.platform.lower()
+
+def matches_environment(requirement):
+    """Filter out requirements that should not be installed
+    in this environment. Only sys_platform is inspected right now.
+    This should be expanded to include other environment markers.
+    See: https://www.python.org/dev/peps/pep-0508/#environment-markers
+    """
+    if 'sys_platform' in requirement.line:
+        match = sys_platform_re.findall(requirement.line)
+        if len(match) > 0:
+            return match[0].lower() == sys_platform
+    return True
+
 def get_requirements_list(requirements_file):
     req_list = list(requirements.parse(requirements_file))
+    req_list = filter(matches_environment, req_list)
     required = [req.name.replace('_', '-') for req in req_list]
     return required
 
diff --git a/test/inspect.test.js b/test/inspect.test.js
index 55cbe4cf..b4958ee8 100644
--- a/test/inspect.test.js
+++ b/test/inspect.test.js
@@ -138,6 +138,32 @@ test('package name differs from requirement', function (t) {
   });
 });
 
+test('package depends on platform', function (t) {
+  chdirWorkspaces('pip-app-deps-conditional');
+  return subProcess.execute('pip',
+    ['install', '-r', 'requirements.txt', '--disable-pip-version-check']
+  )
+  .then(function () {
+    return plugin.inspect('.', 'requirements.txt')
+    .then(function (result) {
+      var pkg = result.package;
+      t.notOk(pkg.dependencies.pypiwin32, 'win32 dep ignored');
+      t.same(pkg.dependencies['posix-ipc'], {
+        from: [
+          'pip-app-deps-conditional@0.0.0',
+          'posix-ipc@1.0.0',
+        ],
+        name: 'posix-ipc',
+        version: '1.0.0',
+      }, 'posix-ipc looks ok');
+      t.end();
+    });
+  })
+  .catch(function (error) {
+    t.fail(error);
+  });
+});
+
 function chdirWorkspaces(dir) {
   process.chdir(path.resolve(__dirname, 'workspaces', dir));
 }
diff --git a/test/workspaces/pip-app-deps-conditional/requirements.txt b/test/workspaces/pip-app-deps-conditional/requirements.txt
new file mode 100644
index 00000000..e87cec37
--- /dev/null
+++ b/test/workspaces/pip-app-deps-conditional/requirements.txt
@@ -0,0 +1,2 @@
+pypiwin32==219; sys_platform == 'win32'
+posix_ipc==1.0.0