diff --git a/lib/puma/request.rb b/lib/puma/request.rb
index 66c9884cca..08b0354819 100644
--- a/lib/puma/request.rb
+++ b/lib/puma/request.rb
@@ -231,7 +231,11 @@ def fetch_status_code(status)
     #
     def normalize_env(env, client)
       if host = env[HTTP_HOST]
-        if colon = host.index(":")
+        # host can be a hostname, ipv4 or bracketed ipv6. Followed by an optional port.
+        if colon = host.rindex("]:") # IPV6 with port
+          env[SERVER_NAME] = host[0, colon+1]
+          env[SERVER_PORT] = host[colon+2, host.bytesize]
+        elsif !host.start_with?("[") && colon = host.index(":") # not hostname or IPV4 with port
           env[SERVER_NAME] = host[0, colon]
           env[SERVER_PORT] = host[colon+1, host.bytesize]
         else
diff --git a/test/test_puma_server.rb b/test/test_puma_server.rb
index 226e85167c..c64ab16099 100644
--- a/test/test_puma_server.rb
+++ b/test/test_puma_server.rb
@@ -53,6 +53,54 @@ def new_connection
     TCPSocket.new(@host, @port).tap {|sock| @ios << sock}
   end
 
+  def test_normalize_host_header_missing
+    server_run app: ->(env) do
+      [200, {}, [env["SERVER_NAME"], "\n", env["SERVER_PORT"]]]
+    end
+
+    data = send_http_and_read "GET / HTTP/1.0\r\n\r\n"
+    assert_equal "localhost\n80", data.split("\r\n").last
+  end
+
+  def test_normalize_host_header_hostname
+    server_run app: ->(env) do
+      [200, {}, [env["SERVER_NAME"], "\n", env["SERVER_PORT"]]]
+    end
+
+    data = send_http_and_read "GET / HTTP/1.0\r\nHost: example.com:456\r\n\r\n"
+    assert_equal "example.com\n456", data.split("\r\n").last
+
+    data = send_http_and_read "GET / HTTP/1.0\r\nHost: example.com\r\n\r\n"
+    assert_equal "example.com\n80", data.split("\r\n").last
+  end
+
+  def test_normalize_host_header_ipv4
+    server_run app: ->(env) do
+      [200, {}, [env["SERVER_NAME"], "\n", env["SERVER_PORT"]]]
+    end
+
+    data = send_http_and_read "GET / HTTP/1.0\r\nHost: 123.123.123.123:456\r\n\r\n"
+    assert_equal "123.123.123.123\n456", data.split("\r\n").last
+
+    data = send_http_and_read "GET / HTTP/1.0\r\nHost: 123.123.123.123\r\n\r\n"
+    assert_equal "123.123.123.123\n80", data.split("\r\n").last
+  end
+
+  def test_normalize_host_header_ipv6
+    server_run app: ->(env) do
+      [200, {}, [env["SERVER_NAME"], "\n", env["SERVER_PORT"]]]
+    end
+
+    data = send_http_and_read "GET / HTTP/1.0\r\nHost: [::ffff:127.0.0.1]:9292\r\n\r\n"
+    assert_equal "[::ffff:127.0.0.1]\n9292", data.split("\r\n").last
+
+    data = send_http_and_read "GET / HTTP/1.0\r\nHost: [::1]:9292\r\n\r\n"
+    assert_equal "[::1]\n9292", data.split("\r\n").last
+
+    data = send_http_and_read "GET / HTTP/1.0\r\nHost: [::1]\r\n\r\n"
+    assert_equal "[::1]\n80", data.split("\r\n").last
+  end
+
   def test_proper_stringio_body
     data = nil