diff --git a/pcie_i2c.hpp b/pcie_i2c.hpp
index 2b572b9..5f1cd35 100644
--- a/pcie_i2c.hpp
+++ b/pcie_i2c.hpp
@@ -18,20 +18,34 @@
 
 #include <ipmid/api.h>
 
+#include <ipmid/api-types.hpp>
+#include <vector>
+
 namespace google
 {
 namespace ipmi
 {
 
+struct PcieSlotCountReply
+{
+    uint8_t value;
+} __attribute__((packed));
+
+struct PcieSlotI2cBusMappingReply
+{
+    uint8_t i2c_bus_number;
+    uint8_t pcie_slot_name_len;
+} __attribute__((packed));
+
 //  Handle the pcie slot count command.
 //  Sys can query the number of pcie slots.
-ipmi_ret_t pcieSlotCount(const uint8_t* reqBuf, uint8_t* replyBuf,
-                         size_t* dataLen, HandlerInterface* handler);
+Resp pcieSlotCount(const std::vector<std::uint8_t>& data,
+                   HandlerInterface* handler);
 
 // Handle the pcie slot to i2c bus mapping command.
 // Sys can query which i2c bus is routed to which pcie slot.
-ipmi_ret_t pcieSlotI2cBusMapping(const uint8_t* reqBuf, uint8_t* replyBuf,
-                                 size_t* dataLen, HandlerInterface* handler);
+Resp pcieSlotI2cBusMapping(const std::vector<std::uint8_t>& data,
+                           HandlerInterface* handler);
 
 } // namespace ipmi
 } // namespace google