diff --git a/beacon_node/eth2_libp2p/src/rpc/codec/ssz_snappy.rs b/beacon_node/eth2_libp2p/src/rpc/codec/ssz_snappy.rs
index 915572fd12a..6d59859315c 100644
--- a/beacon_node/eth2_libp2p/src/rpc/codec/ssz_snappy.rs
+++ b/beacon_node/eth2_libp2p/src/rpc/codec/ssz_snappy.rs
@@ -615,7 +615,11 @@ mod tests {
     type Spec = types::MainnetEthSpec;
 
     fn fork_context() -> ForkContext {
-        ForkContext::new::<Spec>(types::Slot::new(0), Hash256::zero(), &Spec::default_spec())
+        let mut chain_spec = Spec::default_spec();
+        // Set fork_epoch to `Some` to ensure that the `ForkContext` object
+        // includes altair in the list of forks
+        chain_spec.altair_fork_epoch = Some(types::Epoch::new(42));
+        ForkContext::new::<Spec>(types::Slot::new(0), Hash256::zero(), &chain_spec)
     }
 
     fn base_block() -> SignedBeaconBlock<Spec> {
diff --git a/beacon_node/eth2_libp2p/tests/common/mod.rs b/beacon_node/eth2_libp2p/tests/common/mod.rs
index 8c28512d045..1023bbacd40 100644
--- a/beacon_node/eth2_libp2p/tests/common/mod.rs
+++ b/beacon_node/eth2_libp2p/tests/common/mod.rs
@@ -11,14 +11,18 @@ use std::sync::Arc;
 use std::sync::Weak;
 use std::time::Duration;
 use tokio::runtime::Runtime;
-use types::{ChainSpec, EnrForkId, ForkContext, Hash256, MinimalEthSpec};
+use types::{ChainSpec, EnrForkId, EthSpec, ForkContext, Hash256, MinimalEthSpec};
 
 type E = MinimalEthSpec;
 use tempfile::Builder as TempBuilder;
 
 /// Returns a dummy fork context
 fn fork_context() -> ForkContext {
-    ForkContext::new::<E>(types::Slot::new(0), Hash256::zero(), &ChainSpec::minimal())
+    let mut chain_spec = E::default_spec();
+    // Set fork_epoch to `Some` to ensure that the `ForkContext` object
+    // includes altair in the list of forks
+    chain_spec.altair_fork_epoch = Some(types::Epoch::new(42));
+    ForkContext::new::<E>(types::Slot::new(0), Hash256::zero(), &chain_spec)
 }
 
 pub struct Libp2pInstance(LibP2PService<E>, exit_future::Signal);
diff --git a/beacon_node/eth2_libp2p/tests/rpc_tests.rs b/beacon_node/eth2_libp2p/tests/rpc_tests.rs
index 9d1faf748cf..1e5f1e4e1c3 100644
--- a/beacon_node/eth2_libp2p/tests/rpc_tests.rs
+++ b/beacon_node/eth2_libp2p/tests/rpc_tests.rs
@@ -138,11 +138,16 @@ fn test_blocks_by_range_chunked_rpc() {
             step: 0,
         });
 
-        // BlocksByRange Response
         let spec = E::default_spec();
-        let empty_block = BeaconBlock::empty(&spec);
-        let empty_signed = SignedBeaconBlock::from_block(empty_block, Signature::empty());
-        let rpc_response = Response::BlocksByRange(Some(Box::new(empty_signed)));
+
+        // BlocksByRange Response
+        let full_block = BeaconBlock::Base(BeaconBlockBase::<E>::full(&spec));
+        let signed_full_block = SignedBeaconBlock::from_block(full_block, Signature::empty());
+        let rpc_response_base = Response::BlocksByRange(Some(Box::new(signed_full_block)));
+
+        let full_block = BeaconBlock::Altair(BeaconBlockAltair::<E>::full(&spec));
+        let signed_full_block = SignedBeaconBlock::from_block(full_block, Signature::empty());
+        let rpc_response_altair = Response::BlocksByRange(Some(Box::new(signed_full_block)));
 
         // keep count of the number of messages received
         let mut messages_received = 0;
@@ -167,7 +172,11 @@ fn test_blocks_by_range_chunked_rpc() {
                         warn!(log, "Sender received a response");
                         match response {
                             Response::BlocksByRange(Some(_)) => {
-                                assert_eq!(response, rpc_response.clone());
+                                if messages_received < 5 {
+                                    assert_eq!(response, rpc_response_base.clone());
+                                } else {
+                                    assert_eq!(response, rpc_response_altair.clone());
+                                }
                                 messages_received += 1;
                                 warn!(log, "Chunk received");
                             }
@@ -197,7 +206,14 @@ fn test_blocks_by_range_chunked_rpc() {
                         if request == rpc_request {
                             // send the response
                             warn!(log, "Receiver got request");
-                            for _ in 1..=messages_to_send {
+                            for i in 0..messages_to_send {
+                                // Send first half of responses as base blocks and
+                                // second half as altair blocks.
+                                let rpc_response = if i < 5 {
+                                    rpc_response_base.clone()
+                                } else {
+                                    rpc_response_altair.clone()
+                                };
                                 receiver.swarm.behaviour_mut().send_successful_response(
                                     peer_id,
                                     id,
@@ -481,7 +497,7 @@ fn test_blocks_by_root_chunked_rpc() {
     let log_level = Level::Debug;
     let enable_logging = false;
 
-    let messages_to_send = 3;
+    let messages_to_send = 10;
 
     let log = common::build_log(log_level, enable_logging);
     let spec = E::default_spec();
@@ -497,6 +513,13 @@ fn test_blocks_by_root_chunked_rpc() {
                 Hash256::from_low_u64_be(0),
                 Hash256::from_low_u64_be(0),
                 Hash256::from_low_u64_be(0),
+                Hash256::from_low_u64_be(0),
+                Hash256::from_low_u64_be(0),
+                Hash256::from_low_u64_be(0),
+                Hash256::from_low_u64_be(0),
+                Hash256::from_low_u64_be(0),
+                Hash256::from_low_u64_be(0),
+                Hash256::from_low_u64_be(0),
             ]),
         });