diff --git a/lib/mspec/commands/mspec-run.rb b/lib/mspec/commands/mspec-run.rb
index 4d8f4d9..064c177 100644
--- a/lib/mspec/commands/mspec-run.rb
+++ b/lib/mspec/commands/mspec-run.rb
@@ -32,6 +32,7 @@ def options(argv = ARGV)
     options.chdir
     options.prefix
     options.configure { |f| load f }
+    options.env
     options.randomize
     options.repeat
     options.pretend
diff --git a/lib/mspec/utils/options.rb b/lib/mspec/utils/options.rb
index 3b5962d..23cf915 100644
--- a/lib/mspec/utils/options.rb
+++ b/lib/mspec/utils/options.rb
@@ -204,6 +204,13 @@ def configure(&block)
        "Load FILE containing configuration options", &block)
   end
 
+  def env
+    on("--env", "KEY=VALUE", "Set environment variable") do |env|
+      key, value = env.split('=', 2)
+      ENV[key] = value
+    end
+  end
+
   def targets
     on("-t", "--target", "TARGET",
        "Implementation to run the specs, where TARGET is:") do |t|
@@ -484,6 +491,7 @@ def debug
 
   def all
     configure {}
+    env
     targets
     formatters
     filters