diff --git a/spec/http_spec.cr b/spec/http_spec.cr
index 286f7e0..4d76d5e 100644
--- a/spec/http_spec.cr
+++ b/spec/http_spec.cr
@@ -6,9 +6,9 @@ WebMock.stub(:post, "http://example.com/post")
 WebMock.stub(:get, "example.com/%E3%81%82%E3%81%82%E3%81%82")
 WebMock.stub(:get, "https://example.com/")
 WebMock.stub(:get, "https://example.com/post")
-WebMock.stub(:put, "http://example.com/put").
-  with(body: "hello", headers: {"User-Agent" => "Mechanize/0.2.0 Crystal/1.1.1 (https://github.com/Kanezoh/mechanize.cr)"}).
-  to_return(body: "")
+WebMock.stub(:put, "http://example.com/put")
+  .with(body: "hello")
+  .to_return(body: "success")
 
 describe "Mechanize HTTP test" do
   it "simple GET" do
@@ -47,8 +47,9 @@ describe "Mechanize HTTP test" do
   it "simple PUT" do
     agent = Mechanize.new
     page = agent.put("http://example.com/put", body: "hello")
-    #page.body.should eq "success"
-    #page.code.should eq 200
+    agent.get("http://example.com/")
+    page.body.should eq "success"
+    page.code.should eq 200
   end
 
   it "can escape non-ascii character" do
diff --git a/src/mechanize.cr b/src/mechanize.cr
index 98523f2..23220cc 100644
--- a/src/mechanize.cr
+++ b/src/mechanize.cr
@@ -91,22 +91,27 @@ class Mechanize
     post_form(uri, form, headers)
   end
 
-  # Send PUT request to specified uri with headers, and query.
+  # Send PUT request to specified uri with headers, and body.
   #
-  # Examples (send post request whose post body is "foo=bar")
+  # Examples (send put request whose post body is "hello")
   #
   # ```
   # agent = Mechanize.new
   # agent.put("http://example.com",
-  #   body: "hello!",
-  #   headers: HTTP::Headers{"Foo" => "Bar"})
+  #   body: "hello")
   # ```
   def put(uri : String | URI,
           body : String?,
           headers = ::HTTP::Headers.new) : Mechanize::Page
-
     method = :put
+    headers.merge!({
+      "Content-Type"   => "application/octet-stream",
+      "Content-Length" => body.size.to_s,
+    })
+
     page = @agent.fetch(uri, method, headers: headers, body: body)
+    request_headers.delete("Content-Type")
+    request_headers.delete("Content-Length")
     add_to_history(page)
     # yield page if block_given?
     page
@@ -284,8 +289,8 @@ class Mechanize
 
     # fetch the page
     page = @agent.fetch(uri, :post, headers: headers, params: {"value" => request_data}, referer: cur_page)
-    headers.delete("Content-Type")
-    headers.delete("Content-Length")
+    request_headers.delete("Content-Type")
+    request_headers.delete("Content-Length")
     add_to_history(page)
     page
   end