diff --git a/app/proxyman/command/command.go b/app/proxyman/command/command.go
old mode 100644
new mode 100755
index ca0b662c4..e80f3d2c2
--- a/app/proxyman/command/command.go
+++ b/app/proxyman/command/command.go
@@ -37,7 +37,7 @@ func (op *AddUserOperation) ApplyInbound(ctx context.Context, handler core.Inbou
 	}
 	um, ok := p.(proxy.UserManager)
 	if !ok {
-		return newError("proxy is not an UserManager")
+		return newError("proxy is not a UserManager")
 	}
 	return um.AddUser(ctx, op.User)
 }
@@ -50,7 +50,7 @@ func (op *RemoveUserOperation) ApplyInbound(ctx context.Context, handler core.In
 	}
 	um, ok := p.(proxy.UserManager)
 	if !ok {
-		return newError("proxy is not an UserManager")
+		return newError("proxy is not a UserManager")
 	}
 	return um.RemoveUser(ctx, op.Email)
 }
diff --git a/common/protocol/account.go b/common/protocol/account.go
old mode 100644
new mode 100755
index 1c6a1eeaa..7793974a7
--- a/common/protocol/account.go
+++ b/common/protocol/account.go
@@ -1,6 +1,6 @@
 package protocol
 
-// Account is an user identity used for authentication.
+// Account is a user identity used for authentication.
 type Account interface {
 	Equals(Account) bool
 }
diff --git a/common/protocol/context.go b/common/protocol/context.go
old mode 100644
new mode 100755
index 6a2d24090..17437719a
--- a/common/protocol/context.go
+++ b/common/protocol/context.go
@@ -10,12 +10,12 @@ const (
 	userKey key = iota
 )
 
-// ContextWithUser returns a context combined with an User.
+// ContextWithUser returns a context combined with a User.
 func ContextWithUser(ctx context.Context, user *User) context.Context {
 	return context.WithValue(ctx, userKey, user)
 }
 
-// UserFromContext extracts an User from the given context, if any.
+// UserFromContext extracts a User from the given context, if any.
 func UserFromContext(ctx context.Context) *User {
 	v := ctx.Value(userKey)
 	if v == nil {
diff --git a/proxy/proxy.go b/proxy/proxy.go
old mode 100644
new mode 100755
index 0278d1185..a0d0ac422
--- a/proxy/proxy.go
+++ b/proxy/proxy.go
@@ -41,7 +41,7 @@ type UserManager interface {
 	// AddUser adds a new user.
 	AddUser(context.Context, *protocol.User) error
 
-	// RemoveUser removes an user by email.
+	// RemoveUser removes a user by email.
 	RemoveUser(context.Context, string) error
 }