diff --git a/src/proto.rs b/src/proto.rs
index 2bacb44..f33226c 100644
--- a/src/proto.rs
+++ b/src/proto.rs
@@ -37,6 +37,7 @@ pub struct Agent {
 pub struct Property {
 	pub name: String,
 	pub value: String,
+	#[serde(skip_serializing_if = "Option::is_none")]
 	pub signature: Option<String>,
 }
 
@@ -83,7 +84,9 @@ pub struct AuthenticateRequest {
 	pub agent: Agent,
 	pub username: String,
 	pub password: String,
+	#[serde(skip_serializing_if = "Option::is_none")]
 	pub clientToken: Option<String>,
+	#[serde(skip_serializing_if = "Option::is_none")]
 	pub requestUser: Option<bool>,
 }
 
@@ -101,6 +104,7 @@ pub struct RefreshRequest {
 	pub accessToken: String,
 	pub clientToken: String,
 	pub selectedProfile: Option<Profile>,
+	#[serde(skip_serializing_if = "Option::is_none")]
 	pub requestUser: Option<bool>,
 }
 
@@ -109,12 +113,14 @@ pub struct RefreshResponse {
 	pub accessToken: String,
 	pub clientToken: String,
 	pub selectedProfile: Profile,
+	#[serde(skip_serializing_if = "Option::is_none")]
 	pub user: Option<User>,
 }
 
 #[derive(Serialize, Deserialize, Debug)]
 pub struct ValidateRequest {
 	pub accessToken: String,
+	#[serde(skip_serializing_if = "Option::is_none")]
 	pub clientToken: Option<String>,
 }
 
@@ -145,6 +151,7 @@ pub struct AccessToken {
 	pub accessToken: String,
 	pub clientToken: String,
 	pub selectedProfile: Profile,
+	#[serde(skip_serializing_if = "Option::is_none")]
 	pub availableProfiles: Option<Vec<Profile>>,
 }