diff --git a/.travis.yml b/.travis.yml
index 7b652cd25..c9ad822cc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,8 @@ install:
  - go get github.com/golang/lint/golint
  - go get github.com/fzipp/gocyclo
 
-script: gb build github.com/matrix-org/dendrite/roomserver/roomserver && ./hooks/pre-commit
+script:
+ - gb build github.com/matrix-org/dendrite/roomserver/roomserver && ./hooks/pre-commit
 
 notifications:
     webhooks:
diff --git a/README.md b/README.md
index e3fe4e197..636cc49e1 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-# Dendrite
+# Dendrite [![Build Status](https://travis-ci.org/matrix-org/dendrite.svg?branch=master)](https://travis-ci.org/matrix-org/dendrite)
 
 Dendrite will be a matrix homeserver written in go.
 
diff --git a/src/github.com/matrix-org/dendrite/clientapi/clientapi.go b/src/github.com/matrix-org/dendrite/clientapi/clientapi.go
index b646904d9..95055b29e 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/clientapi.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/clientapi.go
@@ -1,18 +1,40 @@
 package main
 
 import (
-	"github.com/matrix-org/dendrite/clientapi/routing"
 	"net/http"
 	"os"
+	"path/filepath"
+
+	"github.com/matrix-org/dendrite/clientapi/routing"
 
 	log "github.com/Sirupsen/logrus"
+	"github.com/matrix-org/dugong"
 )
 
+func setupLogging(logDir string) {
+	_ = os.Mkdir(logDir, os.ModePerm)
+	log.AddHook(dugong.NewFSHook(
+		filepath.Join(logDir, "info.log"),
+		filepath.Join(logDir, "warn.log"),
+		filepath.Join(logDir, "error.log"),
+		&log.TextFormatter{
+			TimestampFormat:  "2006-01-02 15:04:05.000000",
+			DisableColors:    true,
+			DisableTimestamp: false,
+			DisableSorting:   false,
+		}, &dugong.DailyRotationSchedule{GZip: true},
+	))
+}
+
 func main() {
 	bindAddr := os.Getenv("BIND_ADDRESS")
 	if bindAddr == "" {
 		log.Panic("No BIND_ADDRESS environment variable found.")
 	}
+	logDir := os.Getenv("LOG_DIR")
+	if logDir != "" {
+		setupLogging(logDir)
+	}
 	log.Info("Starting clientapi")
 	routing.Setup(http.DefaultServeMux, http.DefaultClient)
 	log.Fatal(http.ListenAndServe(bindAddr, nil))
diff --git a/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror.go b/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror.go
new file mode 100644
index 000000000..a0111197c
--- /dev/null
+++ b/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror.go
@@ -0,0 +1,62 @@
+package jsonerror
+
+import "fmt"
+
+// MatrixError represents the "standard error response" in Matrix.
+// http://matrix.org/docs/spec/client_server/r0.2.0.html#api-standards
+type MatrixError struct {
+	ErrCode string `json:"errcode"`
+	Err     string `json:"error"`
+}
+
+func (e *MatrixError) Error() string {
+	return fmt.Sprintf("%s: %s", e.ErrCode, e.Err)
+}
+
+// Forbidden is an error when the client tries to access a resource
+// they are not allowed to access.
+func Forbidden(msg string) *MatrixError {
+	return &MatrixError{"M_FORBIDDEN", msg}
+}
+
+// BadJSON is an error when the client supplies malformed JSON.
+func BadJSON(msg string) *MatrixError {
+	return &MatrixError{"M_BAD_JSON", msg}
+}
+
+// NotJSON is an error when the client supplies something that is not JSON
+// to a JSON endpoint.
+func NotJSON(msg string) *MatrixError {
+	return &MatrixError{"M_NOT_JSON", msg}
+}
+
+// NotFound is an error when the client tries to access an unknown resource.
+func NotFound(msg string) *MatrixError {
+	return &MatrixError{"M_NOT_FOUND", msg}
+}
+
+// MissingToken is an error when the client tries to access a resource which
+// requires authentication without supplying credentials.
+func MissingToken(msg string) *MatrixError {
+	return &MatrixError{"M_MISSING_TOKEN", msg}
+}
+
+// UnknownToken is an error when the client tries to access a resource which
+// requires authentication and supplies a valid, but out-of-date token.
+func UnknownToken(msg string) *MatrixError {
+	return &MatrixError{"M_UNKNOWN_TOKEN", msg}
+}
+
+// LimitExceededError is a rate-limiting error.
+type LimitExceededError struct {
+	MatrixError
+	RetryAfterMS int64 `json:"retry_after_ms,omitempty"`
+}
+
+// LimitExceeded is an error when the client tries to send events too quickly.
+func LimitExceeded(msg string, retryAfterMS int64) *LimitExceededError {
+	return &LimitExceededError{
+		MatrixError:  MatrixError{"M_LIMIT_EXCEEDED", msg},
+		RetryAfterMS: retryAfterMS,
+	}
+}
diff --git a/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror_test.go b/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror_test.go
new file mode 100644
index 000000000..33e2ede83
--- /dev/null
+++ b/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror_test.go
@@ -0,0 +1,30 @@
+package jsonerror
+
+import (
+	"encoding/json"
+	"testing"
+)
+
+func TestLimitExceeded(t *testing.T) {
+	e := LimitExceeded("too fast", 5000)
+	jsonBytes, err := json.Marshal(&e)
+	if err != nil {
+		t.Fatalf("TestLimitExceeded: Failed to marshal LimitExceeded error. %s", err.Error())
+	}
+	want := `{"errcode":"M_LIMIT_EXCEEDED","error":"too fast","retry_after_ms":5000}`
+	if string(jsonBytes) != want {
+		t.Errorf("TestLimitExceeded: want %s, got %s", want, string(jsonBytes))
+	}
+}
+
+func TestForbidden(t *testing.T) {
+	e := Forbidden("you shall not pass")
+	jsonBytes, err := json.Marshal(&e)
+	if err != nil {
+		t.Fatalf("TestForbidden: Failed to marshal Forbidden error. %s", err.Error())
+	}
+	want := `{"errcode":"M_FORBIDDEN","error":"you shall not pass"}`
+	if string(jsonBytes) != want {
+		t.Errorf("TestForbidden: want %s, got %s", want, string(jsonBytes))
+	}
+}