diff --git a/relay_client/src/client/stream.rs b/relay_client/src/client/stream.rs
index 48d6615..185c59f 100644
--- a/relay_client/src/client/stream.rs
+++ b/relay_client/src/client/stream.rs
@@ -175,7 +175,7 @@ impl ClientStream {
                         Payload::Response(response) => {
                             let id = response.id();
 
-                            if !id.is_valid() {
+                            if id.is_zero() {
                                 return match response {
                                     Response::Error(response) => {
                                         Some(StreamEvent::InboundError(Error::Rpc {
diff --git a/relay_rpc/src/domain.rs b/relay_rpc/src/domain.rs
index 62035bf..4694aa9 100644
--- a/relay_rpc/src/domain.rs
+++ b/relay_rpc/src/domain.rs
@@ -143,11 +143,18 @@ new_type!(
 );
 
 impl MessageId {
-    pub fn is_valid(&self) -> bool {
+    /// Minimum allowed value of a [`MessageId`].
+    const MIN: Self = Self(1000000000);
+
+    pub(crate) fn validate(&self) -> bool {
+        self.0 >= Self::MIN.0
+    }
+
+    pub fn is_zero(&self) -> bool {
         // Message ID `0` is used when the client request failed to parse for whatever
         // reason, and the server doesn't know the message ID of that request, but still
         // wants to communicate the error.
-        self.0 != 0
+        self.0 == 0
     }
 }
 
diff --git a/relay_rpc/src/rpc.rs b/relay_rpc/src/rpc.rs
index 5ccc4d8..f327ba4 100644
--- a/relay_rpc/src/rpc.rs
+++ b/relay_rpc/src/rpc.rs
@@ -37,6 +37,9 @@ pub enum ValidationError {
     #[error("Subscription ID decoding failed: {0}")]
     SubscriptionIdDecoding(DecodingError),
 
+    #[error("Invalid request ID")]
+    RequestId,
+
     #[error("Invalid JSON RPC version")]
     JsonRpcVersion,
 
@@ -701,6 +704,10 @@ impl Request {
 
     /// Validates the request payload.
     pub fn validate(&self) -> Result<(), ValidationError> {
+        if !self.id.validate() {
+            return Err(ValidationError::RequestId);
+        }
+
         if self.jsonrpc.as_ref() != JSON_RPC_VERSION_STR {
             return Err(ValidationError::JsonRpcVersion);
         }
diff --git a/relay_rpc/src/rpc/tests.rs b/relay_rpc/src/rpc/tests.rs
index f7be09d..861ce25 100644
--- a/relay_rpc/src/rpc/tests.rs
+++ b/relay_rpc/src/rpc/tests.rs
@@ -194,13 +194,27 @@ fn deserialize_batch_methods() {
 #[test]
 fn validation() {
     // Valid data.
-    let id = MessageId::from(1);
+    let id = MessageId::from(1234567890);
     let jsonrpc: Arc<str> = "2.0".into();
     let message: Arc<str> = "0".repeat(512).into();
     let topic = Topic::from("c4163cf65859106b3f5435fc296e7765411178ed452d1c30337a6230138c9840");
     let subscription_id =
         SubscriptionId::from("c4163cf65859106b3f5435fc296e7765411178ed452d1c30337a6230138c9841");
 
+    // Invalid request ID.
+    let request = Request {
+        id: MessageId::new(1),
+        jsonrpc: jsonrpc.clone(),
+        params: Params::Publish(Publish {
+            topic: topic.clone(),
+            message: message.clone(),
+            ttl_secs: 0,
+            tag: 0,
+            prompt: false,
+        }),
+    };
+    assert_eq!(request.validate(), Err(ValidationError::RequestId));
+
     // Invalid JSONRPC version.
     let request = Request {
         id,