diff --git a/sys/dev/cxgbe/common/common.h b/sys/dev/cxgbe/common/common.h
index 7a88462a2c5b..820354ab696f 100644
--- a/sys/dev/cxgbe/common/common.h
+++ b/sys/dev/cxgbe/common/common.h
@@ -238,6 +238,7 @@ struct vpd_params {
 
 struct pci_params {
 	unsigned int vpd_cap_addr;
+	unsigned int mps;
 	unsigned short speed;
 	unsigned short width;
 };
diff --git a/sys/dev/cxgbe/t4_main.c b/sys/dev/cxgbe/t4_main.c
index 8089eb4cf053..f9caf2eec1d8 100644
--- a/sys/dev/cxgbe/t4_main.c
+++ b/sys/dev/cxgbe/t4_main.c
@@ -594,6 +594,8 @@ t4_attach(device_t dev)
 		v = pci_read_config(dev, i + PCIER_DEVICE_CTL, 2);
 		v |= PCIEM_CTL_RELAXED_ORD_ENABLE;
 		pci_write_config(dev, i + PCIER_DEVICE_CTL, v, 2);
+
+		sc->params.pci.mps = 128 << ((v & PCIEM_CTL_MAX_PAYLOAD) >> 5);
 	}
 
 	sc->traceq = -1;