diff --git a/lib/remote_storage/swift.rb b/lib/remote_storage/swift.rb
index fbab446..2593fde 100644
--- a/lib/remote_storage/swift.rb
+++ b/lib/remote_storage/swift.rb
@@ -139,10 +139,10 @@ module RemoteStorage
       url = url_for_key(user, directory, key)
 
       if required_match = server.env["HTTP_IF_MATCH"]
-        server.halt 412 unless required_match == %Q("#{existing_metadata["e"]}")
+        server.halt 412, "Precondition Failed" unless required_match == %Q("#{existing_metadata["e"]}")
       end
       if server.env["HTTP_IF_NONE_MATCH"] == "*"
-        server.halt 412 unless existing_metadata.empty?
+        server.halt 412, "Precondition Failed" unless existing_metadata.empty?
       end
 
       res = do_put_request(url, data, content_type)
@@ -178,7 +178,7 @@ module RemoteStorage
       existing_metadata = redis.hgetall "rs:m:#{user}:#{directory}/#{key}"
 
       if required_match = server.env["HTTP_IF_MATCH"]
-        server.halt 412 unless required_match == %Q("#{existing_metadata["e"]}")
+        server.halt 412, "Precondition Failed" unless required_match == %Q("#{existing_metadata["e"]}")
       end
 
       do_delete_request(url)
diff --git a/spec/swift/app_spec.rb b/spec/swift/app_spec.rb
index ecb0e4f..298ab29 100644
--- a/spec/swift/app_spec.rb
+++ b/spec/swift/app_spec.rb
@@ -165,7 +165,82 @@ describe "App" do
           last_response.status.must_equal 400
         end
       end
+
+      describe "If-Match header" do
+        before do
+          put_stub = OpenStruct.new(headers: {
+            etag: "oldetag",
+            last_modified: "Fri, 04 Mar 2016 12:20:18 GMT"
+          })
+
+          RestClient.stub :put, put_stub do
+            put "/phil/food/aguacate", "si"
+          end
+        end
+
+        it "allows the request if the header matches the current ETag" do
+          header "If-Match", "\"oldetag\""
+
+          put_stub = OpenStruct.new(headers: {
+            etag: "newetag",
+            last_modified: "Fri, 04 Mar 2016 12:20:18 GMT"
+          })
+
+          RestClient.stub :put, put_stub do
+            put "/phil/food/aguacate", "aye"
+          end
+
+          last_response.status.must_equal 200
+          last_response.headers["Etag"].must_equal "\"newetag\""
+        end
+
+        it "fails the request if the header does not match the current ETag" do
+          header "If-Match", "someotheretag"
+
+          put "/phil/food/aguacate", "aye"
+
+          last_response.status.must_equal 412
+          last_response.body.must_equal "Precondition Failed"
+        end
+      end
+
+      describe "If-None-Match header set to '*'" do
+        it "succeeds when the document doesn't exist yet" do
+          put_stub = OpenStruct.new(headers: {
+            etag: "someetag",
+            last_modified: "Fri, 04 Mar 2016 12:20:18 GMT"
+          })
+
+          header "If-None-Match", "*"
+
+          RestClient.stub :put, put_stub do
+            put "/phil/food/aguacate", "si"
+          end
+
+          last_response.status.must_equal 200
+        end
+
+        it "fails the request if the document already exsits" do
+          put_stub = OpenStruct.new(headers: {
+            etag: "someetag",
+            last_modified: "Fri, 04 Mar 2016 12:20:18 GMT"
+          })
+
+          RestClient.stub :put, put_stub do
+            put "/phil/food/aguacate", "si"
+          end
+
+          header "If-None-Match", "*"
+          RestClient.stub :put, put_stub do
+            put "/phil/food/aguacate", "si"
+          end
+
+          last_response.status.must_equal 412
+          last_response.body.must_equal "Precondition Failed"
+        end
+      end
     end
+
   end
 
   describe "DELETE requests" do
@@ -273,6 +348,27 @@ describe "App" do
         last_response.status.must_equal 404
         last_response.body.must_equal "Not Found"
       end
+
+      describe "If-Match header" do
+        it "succeeds when the header matches the current ETag" do
+          header "If-Match", "\"bla\""
+
+          RestClient.stub :delete, "" do
+            delete "/phil/food/aguacate"
+          end
+
+          last_response.status.must_equal 200
+        end
+
+        it "fails the request if it does not match the current ETag" do
+          header "If-Match", "someotheretag"
+
+          delete "/phil/food/aguacate"
+
+          last_response.status.must_equal 412
+          last_response.body.must_equal "Precondition Failed"
+        end
+      end
     end
   end