diff --git a/spec/frank_handler_spec.cr b/spec/frank_handler_spec.cr
index de87e7e..e9ef151 100644
--- a/spec/frank_handler_spec.cr
+++ b/spec/frank_handler_spec.cr
@@ -10,4 +10,14 @@ describe "Frank::Handler" do
     response = frank.call(request)
     response.body.should eq("hello")
   end
+
+  it "sets content type" do
+    frank = Frank::Handler.new
+    frank.add_route "GET", "/" do |env|
+      env.response.content_type = "application/json"
+    end
+    request = HTTP::Request.new("GET", "/")
+    response = frank.call(request)
+    response.headers["Content-Type"].should eq("application/json")
+  end
 end
diff --git a/src/frank/context.cr b/src/frank/context.cr
new file mode 100644
index 0000000..be38087
--- /dev/null
+++ b/src/frank/context.cr
@@ -0,0 +1,14 @@
+class Frank::Context
+  getter request
+
+  def initialize(@request)
+  end
+
+  def response
+    @response ||= Response.new
+  end
+
+  def response?
+    @response
+  end
+end
diff --git a/src/frank/dsl.cr b/src/frank/dsl.cr
index 8241982..2165f7d 100644
--- a/src/frank/dsl.cr
+++ b/src/frank/dsl.cr
@@ -1,7 +1,7 @@
-def get(path, &block : Frank::Request -> String)
+def get(path, &block : Frank::Context -> _)
   Frank::Handler::INSTANCE.add_route("GET", path, &block)
 end
 
-def post(path, &block : Frank::Request -> String)
+def post(path, &block : Frank::Context -> _)
   Frank::Handler::INSTANCE.add_route("POST", path, &block)
 end
diff --git a/src/frank/handler.cr b/src/frank/handler.cr
index e28f432..efe51bf 100644
--- a/src/frank/handler.cr
+++ b/src/frank/handler.cr
@@ -8,18 +8,11 @@ class Frank::Handler < HTTP::Handler
   end
 
   def call(request)
-    if body = exec_request(request)
-      begin
-        HTTP::Response.new("HTTP/1.1", 200, "OK", {"Content-Type" => "text/plain"}, body)
-      rescue ex
-        HTTP::Response.new("HTTP/1.1", 500, "Internal Server Error", {"Content-Type" => "text/plain"}, ex.to_s)
-      end
-    else
-      call_next(request)
-    end
+    response = exec_request(request)
+    response || call_next(request)
   end
 
-  def add_route(method, path, &handler : Frank::Request -> String)
+  def add_route(method, path, &handler : Frank::Context -> _)
     @routes << Route.new(method, path, &handler)
   end
 
@@ -29,7 +22,14 @@ class Frank::Handler < HTTP::Handler
       params = route.match(request.method, components)
       if params
         frank_request = Request.new(params)
-        return route.handler.call(frank_request)
+        context = Context.new(frank_request)
+        begin
+          body = route.handler.call(context).to_s
+          content_type = context.response?.try(&.content_type) || "text/plain"
+          return HTTP::Response.new("HTTP/1.1", 200, "OK", {"Content-Type" => content_type}, body)
+        rescue ex
+          return HTTP::Response.new("HTTP/1.1", 500, "Internal Server Error", {"Content-Type" => "text/plain"}, ex.to_s)
+        end
       end
     end
     nil
diff --git a/src/frank/response.cr b/src/frank/response.cr
new file mode 100644
index 0000000..b2cb1a1
--- /dev/null
+++ b/src/frank/response.cr
@@ -0,0 +1,3 @@
+class Frank::Response
+  property content_type
+end
diff --git a/src/frank/route.cr b/src/frank/route.cr
index fce5dae..0c29664 100644
--- a/src/frank/route.cr
+++ b/src/frank/route.cr
@@ -1,7 +1,7 @@
 class Frank::Route
   getter handler
 
-  def initialize(@method, path, &@handler : Frank::Request -> String)
+  def initialize(@method, path, &@handler : Frank::Context -> _)
     @components = path.split "/"
   end