diff --git a/services/commtest/tests/lib/tools.rs b/services/commtest/tests/lib/tools.rs
index 6df15de8d..ade4e4d2d 100644
--- a/services/commtest/tests/lib/tools.rs
+++ b/services/commtest/tests/lib/tools.rs
@@ -1,22 +1,29 @@
 use bytesize::ByteSize;
 
 #[allow(dead_code)]
 pub fn generate_nbytes(number_of_bytes: usize, predefined_byte_value: Option<u8>) -> Vec<u8> {
   let byte_value = predefined_byte_value.unwrap_or(b'A');
   return vec![byte_value; number_of_bytes];
 }
 
 #[derive(
   Debug, derive_more::Display, derive_more::From, derive_more::Error,
 )]
 pub enum Error {
   #[display(...)]
   Proto(std::io::Error),
   #[display(...)]
   Tonic(tonic::transport::Error),
   #[display(...)]
   TonicStatus(tonic::Status),
 }
 
+pub const GRPC_METADATA_SIZE_BYTES: usize = 5;
+
+#[allow(dead_code)]
+pub fn get_grpc_chunk_size_limit() -> usize {
+  (ByteSize::mib(4).as_u64() as usize) - GRPC_METADATA_SIZE_BYTES
+}
+
 #[allow(dead_code)]
 pub const ATTACHMENT_DELIMITER: &str = ";";