diff --git a/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror.go b/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror.go
index 2ba9db328..07fe90304 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/jsonerror/jsonerror.go
@@ -73,10 +73,10 @@ func MissingArgument(msg string) *MatrixError {
 	return &MatrixError{"M_MISSING_ARGUMENT", msg}
 }
 
-// InvalidArgumentBody is an error when the client tries to provide an
-// invalid body under a valid argument
-func InvalidArgumentBody(msg string) *MatrixError {
-	return &MatrixError{"M_INVALID_ARGUMENT_BODY", msg}
+// InvalidArgumentValue is an error when the client tries to provide an
+// invalid value for a valid argument
+func InvalidArgumentValue(msg string) *MatrixError {
+	return &MatrixError{"M_INVALID_ARGUMENT_VALUE", msg}
 }
 
 // MissingToken is an error when the client tries to access a resource which
diff --git a/src/github.com/matrix-org/dendrite/clientapi/routing/profile.go b/src/github.com/matrix-org/dendrite/clientapi/routing/profile.go
index da47451fa..1403a8292 100644
--- a/src/github.com/matrix-org/dendrite/clientapi/routing/profile.go
+++ b/src/github.com/matrix-org/dendrite/clientapi/routing/profile.go
@@ -31,19 +31,6 @@ import (
 	"github.com/matrix-org/util"
 )
 
-type profileResponse struct {
-	AvatarURL   string `json:"avatar_url"`
-	DisplayName string `json:"displayname"`
-}
-
-type avatarURL struct {
-	AvatarURL string `json:"avatar_url"`
-}
-
-type displayName struct {
-	DisplayName string `json:"displayname"`
-}
-
 // GetProfile implements GET /profile/{userID}
 func GetProfile(
 	req *http.Request, accountDB *accounts.Database, userID string,
@@ -63,7 +50,7 @@ func GetProfile(
 	if err != nil {
 		return httputil.LogThenError(req, err)
 	}
-	res := profileResponse{
+	res := common.ProfileResponse{
 		AvatarURL:   profile.AvatarURL,
 		DisplayName: profile.DisplayName,
 	}
@@ -86,7 +73,7 @@ func GetAvatarURL(
 	if err != nil {
 		return httputil.LogThenError(req, err)
 	}
-	res := avatarURL{
+	res := common.AvatarURL{
 		AvatarURL: profile.AvatarURL,
 	}
 	return util.JSONResponse{
@@ -110,7 +97,7 @@ func SetAvatarURL(
 
 	changedKey := "avatar_url"
 
-	var r avatarURL
+	var r common.AvatarURL
 	if resErr := httputil.UnmarshalJSONRequest(req, &r); resErr != nil {
 		return *resErr
 	}
@@ -178,7 +165,7 @@ func GetDisplayName(
 	if err != nil {
 		return httputil.LogThenError(req, err)
 	}
-	res := displayName{
+	res := common.DisplayName{
 		DisplayName: profile.DisplayName,
 	}
 	return util.JSONResponse{
@@ -202,7 +189,7 @@ func SetDisplayName(
 
 	changedKey := "displayname"
 
-	var r displayName
+	var r common.DisplayName
 	if resErr := httputil.UnmarshalJSONRequest(req, &r); resErr != nil {
 		return *resErr
 	}
diff --git a/src/github.com/matrix-org/dendrite/common/types.go b/src/github.com/matrix-org/dendrite/common/types.go
index 471a2f30b..d8c5c5a7e 100644
--- a/src/github.com/matrix-org/dendrite/common/types.go
+++ b/src/github.com/matrix-org/dendrite/common/types.go
@@ -20,3 +20,19 @@ type AccountData struct {
 	RoomID string `json:"room_id"`
 	Type   string `json:"type"`
 }
+
+// ProfileResponse is a struct containing all known user profile data
+type ProfileResponse struct {
+	AvatarURL   string `json:"avatar_url"`
+	DisplayName string `json:"displayname"`
+}
+
+// AvatarURL is a struct containing only the URL to a user's avatar
+type AvatarURL struct {
+	AvatarURL string `json:"avatar_url"`
+}
+
+// DisplayName is a struct containing only a user's display name
+type DisplayName struct {
+	DisplayName string `json:"displayname"`
+}
diff --git a/src/github.com/matrix-org/dendrite/federationapi/routing/profile.go b/src/github.com/matrix-org/dendrite/federationapi/routing/profile.go
index 04ed99657..67703931e 100644
--- a/src/github.com/matrix-org/dendrite/federationapi/routing/profile.go
+++ b/src/github.com/matrix-org/dendrite/federationapi/routing/profile.go
@@ -20,24 +20,12 @@ import (
 	"github.com/matrix-org/dendrite/clientapi/auth/storage/accounts"
 	"github.com/matrix-org/dendrite/clientapi/httputil"
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/common"
 	"github.com/matrix-org/gomatrixserverlib"
 	"github.com/matrix-org/util"
 )
 
-type profileResponse struct {
-	AvatarURL   string `json:"avatar_url"`
-	DisplayName string `json:"displayname"`
-}
-
-type avatarURL struct {
-	AvatarURL string `json:"avatar_url"`
-}
-
-type displayName struct {
-	DisplayName string `json:"displayname"`
-}
-
-// GetProfile implements /_matrix/federation/v1/query/profile
+// GetProfile implements GET /_matrix/federation/v1/query/profile
 func GetProfile(
 	httpReq *http.Request,
 	accountDB *accounts.Database,
@@ -68,19 +56,19 @@ func GetProfile(
 	if field != "" {
 		switch field {
 		case "displayname":
-			res = displayName{
+			res = common.DisplayName{
 				profile.DisplayName,
 			}
 		case "avatar_url":
-			res = avatarURL{
+			res = common.AvatarURL{
 				profile.AvatarURL,
 			}
 		default:
 			code = 400
-			res = jsonerror.InvalidArgumentBody("The request body did not contain allowed values of argument 'field'. Allowed: 'avatar_url', 'displayname'.")
+			res = jsonerror.InvalidArgumentValue("The request body did not contain an allowed value of argument 'field'. Allowed values are either: 'avatar_url', 'displayname'.")
 		}
 	} else {
-		res = profileResponse{
+		res = common.ProfileResponse{
 			profile.AvatarURL,
 			profile.DisplayName,
 		}