diff --git a/engineioxide/Cargo.toml b/engineioxide/Cargo.toml
index 664ec5bb..4e0aa502 100644
--- a/engineioxide/Cargo.toml
+++ b/engineioxide/Cargo.toml
@@ -42,6 +42,7 @@ smallvec = { version = "1.13.1", features = ["union"] }
 tracing = { workspace = true, optional = true }
 
 # Engine.io V3 payload
+itoa = { workspace = true, optional = true }
 memchr = { version = "2.5.0", optional = true }
 unicode-segmentation = { version = "1.10.1", optional = true }
 
@@ -53,7 +54,7 @@ axum.workspace = true
 hyper-util = { workspace = true, features = ["tokio", "client-legacy"] }
 
 [features]
-v3 = ["memchr", "unicode-segmentation"]
+v3 = ["memchr", "unicode-segmentation", "itoa"]
 tracing = ["dep:tracing"]
 
 [[bench]]
diff --git a/engineioxide/src/transport/polling/payload/encoder.rs b/engineioxide/src/transport/polling/payload/encoder.rs
index 839391fa..fad71f43 100644
--- a/engineioxide/src/transport/polling/payload/encoder.rs
+++ b/engineioxide/src/transport/polling/payload/encoder.rs
@@ -116,19 +116,16 @@ pub fn v3_bin_packet_encoder(packet: Packet, data: &mut bytes::BytesMut) -> Resu
     use crate::transport::polling::payload::BINARY_PACKET_SEPARATOR_V3;
     use bytes::BufMut;
 
+    let mut itoa = itoa::Buffer::new();
     match packet {
         Packet::BinaryV3(bin) => {
-            let len = (bin.len() + 1).to_string();
-            let len_len = if let (_, Some(upper)) = len.chars().size_hint() {
-                upper
-            } else {
-                0
-            };
+            let len = itoa.format(bin.len() + 1);
+            let len_len = len.len(); // len is guaranteed to be ascii
 
             data.reserve(1 + len_len + 2 + bin.len());
 
-            data.put_u8(0x1);
-            for char in len.chars() {
+            data.put_u8(0x1); // 1 = binary
+            for char in len.bytes() {
                 data.put_u8(char as u8 - 48);
             }
             data.put_u8(BINARY_PACKET_SEPARATOR_V3); // separator
@@ -137,17 +134,13 @@ pub fn v3_bin_packet_encoder(packet: Packet, data: &mut bytes::BytesMut) -> Resu
         }
         packet => {
             let packet: String = packet.try_into()?;
-            let len = packet.len().to_string();
-            let len_len = if let (_, Some(upper)) = len.chars().size_hint() {
-                upper
-            } else {
-                0
-            };
+            let len = itoa.format(packet.len() + 1);
+            let len_len = len.len(); // len is guaranteed to be ascii
 
             data.reserve(1 + len_len + 1 + packet.as_bytes().len());
 
             data.put_u8(0x0); // 0 = string
-            for char in len.chars() {
+            for char in len.bytes() {
                 data.put_u8(char as u8 - 48);
             }
             data.put_u8(BINARY_PACKET_SEPARATOR_V3); // separator