diff --git a/lib/vagrant/action/builtin/box_add.rb b/lib/vagrant/action/builtin/box_add.rb
index 45a9f3129..d96b25d9a 100644
--- a/lib/vagrant/action/builtin/box_add.rb
+++ b/lib/vagrant/action/builtin/box_add.rb
@@ -114,8 +114,17 @@ module Vagrant
             version: metadata_version.version,
             provider: metadata_provider.name))
 
-          # TODO(mitchellh): verify that the box we're adding
-          # doesn't already exist.
+          # Verify the box we're adding doesn't already exist
+          if !env[:box_force]
+            box = env[:box_collection].find(
+              metadata.name, metadata_provider.name, metadata_version.version)
+            if box
+              raise Errors::BoxAlreadyExists,
+                name: metadata.name,
+                provider: metadata_provider.name,
+                version: metadata_version.version
+            end
+          end
 
           # Now we have a URL, we have to download this URL.
           box = nil
diff --git a/lib/vagrant/errors.rb b/lib/vagrant/errors.rb
index 36d278a69..7453d3c72 100644
--- a/lib/vagrant/errors.rb
+++ b/lib/vagrant/errors.rb
@@ -129,7 +129,7 @@ module Vagrant
     end
 
     class BoxAlreadyExists < VagrantError
-      error_key(:already_exists, "vagrant.actions.box.unpackage")
+      error_key(:box_add_exists)
     end
 
     class BoxChecksumInvalidType < VagrantError
diff --git a/templates/locales/en.yml b/templates/locales/en.yml
index 51bd723f0..d8398954d 100644
--- a/templates/locales/en.yml
+++ b/templates/locales/en.yml
@@ -4,6 +4,13 @@ en:
       Machine booted and ready!
     boot_waiting: |-
       Waiting for machine to boot. This may take a few minutes...
+    box_add_exists: |-
+      The box you're attempting to add already exists. Remove it before
+      adding it again or add it with the `--force` flag.
+
+      Name: %{name}
+      Provider: %{provider}
+      Version: %{version}
     box_add_with_version: |-
       Adding box '%{name}' (v%{version}) for '%{provider}' provider...
     box_added: |-
@@ -1252,12 +1259,6 @@ en:
             output from attempting to unpackage (if any):
 
             %{output}
-          already_exists: |-
-            The box you're attempting to add already exists:
-
-            Name: %{name}
-            Version: %{version}
-            Provider: %{providers}
         add:
           adding: |-
             Extracting box...
diff --git a/test/unit/vagrant/action/builtin/box_add_test.rb b/test/unit/vagrant/action/builtin/box_add_test.rb
index c9551be28..3439b159a 100644
--- a/test/unit/vagrant/action/builtin/box_add_test.rb
+++ b/test/unit/vagrant/action/builtin/box_add_test.rb
@@ -32,6 +32,10 @@ describe Vagrant::Action::Builtin::BoxAdd do
     FileChecksum.new(path, Digest::SHA1).checksum
   end
 
+  before do
+    box_collection.stub(find: nil)
+  end
+
   context "with box file directly" do
     it "adds it" do
       box_path = iso_env.box2_file(:virtualbox)
@@ -369,6 +373,41 @@ describe Vagrant::Action::Builtin::BoxAdd do
         to raise_error(Vagrant::Errors::BoxAddNoMatchingProvider)
     end
 
+    it "raises an error if a box already exists" do
+      box_path = iso_env.box2_file(:virtualbox)
+      tf = Tempfile.new("vagrant").tap do |f|
+        f.write(<<-RAW)
+        {
+          "name": "foo/bar",
+          "versions": [
+            {
+              "version": "0.5"
+            },
+            {
+              "version": "0.7",
+              "providers": [
+                {
+                  "name": "virtualbox",
+                  "url":  "#{box_path}"
+                }
+              ]
+            }
+          ]
+        }
+        RAW
+        f.close
+      end
+
+      env[:box_url] = tf.path
+      box_collection.should_receive(:find).
+        with("foo/bar", "virtualbox", "0.7").and_return(box)
+      box_collection.should_receive(:add).never
+      app.should_receive(:call).never
+
+      expect { subject.call(env) }.
+        to raise_error(Vagrant::Errors::BoxAlreadyExists)
+    end
+
     it "force adds a box if specified" do
       box_path = iso_env.box2_file(:virtualbox)
       tf = Tempfile.new("vagrant").tap do |f|
@@ -396,6 +435,7 @@ describe Vagrant::Action::Builtin::BoxAdd do
 
       env[:box_force] = true
       env[:box_url] = tf.path
+      box_collection.stub(find: box)
       box_collection.should_receive(:add).with do |path, name, version, **opts|
         expect(checksum(path)).to eq(checksum(box_path))
         expect(name).to eq("foo/bar")