diff --git a/crates/format/src/case.rs b/crates/format/src/case.rs
index 26e803e..ccb9394 100644
--- a/crates/format/src/case.rs
+++ b/crates/format/src/case.rs
@@ -9,13 +9,19 @@ use crate::{
 
 #[derive(Debug, Default, Serialize, Deserialize, Clone, Eq, PartialEq)]
 pub struct Case {
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub name: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub comment: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub modes: Option<Vec<Mode>>,
     #[serde(rename = "inputs")]
     pub steps: Vec<Step>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub group: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub expected: Option<Expected>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub ignore: Option<bool>,
 }
 
diff --git a/crates/format/src/input.rs b/crates/format/src/input.rs
index d742f3a..1b80e97 100644
--- a/crates/format/src/input.rs
+++ b/crates/format/src/input.rs
@@ -36,20 +36,29 @@ pub enum Step {
 pub struct Input {
     #[serde(default = "Input::default_caller")]
     pub caller: Address,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub comment: Option<String>,
     #[serde(default = "Input::default_instance")]
     pub instance: ContractInstance,
     pub method: Method,
     #[serde(default)]
     pub calldata: Calldata,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub expected: Option<Expected>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub value: Option<EtherValue>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub storage: Option<HashMap<String, Calldata>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub variable_assignments: Option<VariableAssignments>,
 }
 
 #[derive(Clone, Debug, Default, Serialize, Deserialize, Eq, PartialEq)]
 pub struct BalanceAssertion {
+    /// An optional comment on the balance assertion.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub comment: Option<String>,
+
     /// The address that the balance assertion should be done on.
     ///
     /// This is a string which will be resolved into an address when being processed. Therefore,
@@ -64,6 +73,10 @@ pub struct BalanceAssertion {
 
 #[derive(Clone, Debug, Default, Serialize, Deserialize, Eq, PartialEq)]
 pub struct StorageEmptyAssertion {
+    /// An optional comment on the storage empty assertion.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub comment: Option<String>,
+
     /// The address that the balance assertion should be done on.
     ///
     /// This is a string which will be resolved into an address when being processed. Therefore,
@@ -86,8 +99,11 @@ pub enum Expected {
 
 #[derive(Clone, Debug, Default, Serialize, Deserialize, Eq, PartialEq)]
 pub struct ExpectedOutput {
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub compiler_version: Option<VersionReq>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub return_data: Option<Calldata>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub events: Option<Vec<Event>>,
     #[serde(default)]
     pub exception: bool,
@@ -95,6 +111,7 @@ pub struct ExpectedOutput {
 
 #[derive(Clone, Debug, Default, Serialize, Deserialize, Eq, PartialEq)]
 pub struct Event {
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub address: Option<String>,
     pub topics: Vec<String>,
     pub values: Calldata,
diff --git a/crates/format/src/metadata.rs b/crates/format/src/metadata.rs
index 1255187..99debe3 100644
--- a/crates/format/src/metadata.rs
+++ b/crates/format/src/metadata.rs
@@ -45,12 +45,18 @@ impl Deref for MetadataFile {
 
 #[derive(Debug, Default, Serialize, Deserialize, Clone, Eq, PartialEq)]
 pub struct Metadata {
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub targets: Option<Vec<String>>,
     pub cases: Vec<Case>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub contracts: Option<BTreeMap<ContractInstance, ContractPathAndIdent>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub libraries: Option<BTreeMap<PathBuf, BTreeMap<ContractIdent, ContractInstance>>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub ignore: Option<bool>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub modes: Option<Vec<Mode>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub file_path: Option<PathBuf>,
 }