diff --git a/lib/psenv/environment.rb b/lib/psenv/environment.rb
index 33a5be7..ad2e01c 100644
--- a/lib/psenv/environment.rb
+++ b/lib/psenv/environment.rb
@@ -1,11 +1,11 @@
 module Psenv
   class Environment < Hash
     def apply
-      each { |k, v| ENV.store(k, v) unless ENV.has_key?(k) }
+      each { |k, v| ENV.store(k.to_s, v) unless ENV.has_key?(k.to_s) }
     end
 
     def apply!
-      each { |k, v| ENV.store(k, v) }
+      each { |k, v| ENV.store(k.to_s, v) }
     end
 
     def self.create(*variables)
diff --git a/spec/environment_spec.rb b/spec/environment_spec.rb
new file mode 100644
index 0000000..2b29040
--- /dev/null
+++ b/spec/environment_spec.rb
@@ -0,0 +1,63 @@
+require "spec_helper"
+
+RSpec.describe Psenv::Environment do
+  let(:environment1) { { A: "1", B: "1" } }
+  let(:environment2) { { B: "2", C: "2" } }
+
+  context ".create" do
+    subject { Psenv::Environment.create(environment1, environment2) }
+
+    it "returns an environment object" do
+      expect(subject).to be_kind_of(Psenv::Environment)
+    end
+
+    it "is also a hash" do
+      expect(subject).to be_kind_of(Hash)
+    end
+
+    it "creates the correct environment" do
+      expected = { A: "1", B: "1", C: "2" }
+      expect(subject).to eq(expected)
+    end
+  end
+
+  context "#apply" do
+    before(:each) do
+      ENV.store("A", "0")
+      environment = Psenv::Environment.create(environment1, environment2)
+      environment.apply
+    end
+
+    it "does not overwrite existing environment" do
+      expect(ENV["A"]).to eq("0")
+    end
+
+    it "applies unique variables as expected" do
+      expect(ENV["C"]).to eq("2")
+    end
+
+    it "applies duplicates based on the first provided" do
+      expect(ENV["B"]).to eq("1")
+    end
+  end
+
+  context "#apply!" do
+    before(:each) do
+      ENV.store("A", "0")
+      environment = Psenv::Environment.create(environment1, environment2)
+      environment.apply!
+    end
+
+    it "does overwrite existing environment" do
+      expect(ENV["A"]).to eq("1")
+    end
+
+    it "applies unique variables as expected" do
+      expect(ENV["C"]).to eq("2")
+    end
+
+    it "applies duplicates based on the first provided" do
+      expect(ENV["B"]).to eq("1")
+    end 
+  end
+end