diff --git a/ec/Cargo.lock b/ec/Cargo.lock
index 36fa8f3..1a35313 100644
--- a/ec/Cargo.lock
+++ b/ec/Cargo.lock
@@ -491,6 +491,7 @@ dependencies = [
  "num_enum",
  "scopeguard",
  "serialport",
+ "smbus-pec",
  "thermal-service-messages",
  "time-alarm-service-messages",
  "uuid",
diff --git a/ec/test-lib/Cargo.toml b/ec/test-lib/Cargo.toml
index 5be842f..195758c 100644
--- a/ec/test-lib/Cargo.toml
+++ b/ec/test-lib/Cargo.toml
@@ -29,6 +29,7 @@ scopeguard = { version = "1.2" }
 
 # Serial specific
 serialport = { version = "4.8.1" }
+smbus-pec = "1.0.1"
 embedded-services = { git = "https://github.com/OpenDevicePartnership/embedded-services", branch = "v0.2.0" }
 thermal-service-messages = { git = "https://github.com/OpenDevicePartnership/embedded-services", branch = "v0.2.0" }
 
diff --git a/ec/test-lib/src/serial.rs b/ec/test-lib/src/serial.rs
index bca1d94..eb3cb92 100644
--- a/ec/test-lib/src/serial.rs
+++ b/ec/test-lib/src/serial.rs
@@ -184,6 +184,8 @@ impl Serial {
             .map_err(|e| Error::Io(format!("{e:?}")))?;
         port.write_all(&buffer[..HEADER_SZ + request_sz])
             .map_err(|e| Error::Io(format!("{e:?}")))?;
+        let pec = smbus_pec::pec(&buffer[..HEADER_SZ + request_sz]);
+        port.write_all(&[pec]).map_err(|e| Error::Io(format!("{e:?}")))?;
         port.flush().map_err(|e| Error::Io(format!("{e:?}")))?;
 
         // Read response packets
@@ -207,6 +209,16 @@ impl Serial {
                 .ok_or_else(|| Error::Protocol("Response does not fit in buffer".into()))?;
             port.read_exact(packet_slice).map_err(|e| Error::Io(format!("{e:?}")))?;
 
+            let mut pec_buf = [0u8; 1];
+            port.read_exact(&mut pec_buf).map_err(|e| Error::Io(format!("{e:?}")))?;
+            let computed = smbus_pec::pec(&buffer[..SMBUS_HEADER_SZ + len]);
+            if pec_buf[0] != computed {
+                return Err(Error::Protocol(format!(
+                    "PEC mismatch: received {:#04x}, computed {:#04x}",
+                    pec_buf[0], computed
+                )));
+            }
+
             let flags = buffer[MCTP_FLAGS_IDX];
 
             // If this is a SOM packet, skip ODP header (we don't use it) and grab the command code/discriminant