diff --git a/lib_cxng/include/lcx_crc.h b/lib_cxng/include/lcx_crc.h
index 98fb545f..b68d5a68 100644
--- a/lib_cxng/include/lcx_crc.h
+++ b/lib_cxng/include/lcx_crc.h
@@ -60,6 +60,35 @@ uint16_t cx_crc16(const void *buffer, size_t len);
  */
 uint16_t cx_crc16_update(uint16_t crc, const void *buffer, size_t len);
 
+/** CRC32 initial value */
+#define CX_CRC32_INIT 0xFFFFFFFF
+
+/**
+ * @brief   Computes a 32-bit checksum value.
+ *
+ * @details The 32-bit value is computed according to the CRC32 CCITT definition.
+ *
+ * @param[in] buffer The buffer to compute the CRC over.
+ *
+ * @param[in] len    Bytes length of the buffer.
+ *
+ * @return           Current CRC value.
+ */
+uint32_t cx_crc32(const void *buf, size_t len);
+
+/**
+ * @brief   Accumulates more data to CRC.
+ *
+ * @param[in] crc    CRC value to be updated.
+ *
+ * @param[in] buffer The buffer to compute the CRC over.
+ *
+ * @param[in] len    Bytes length of the buffer.
+ *
+ * @return           Updated CRC value.
+ */
+uint32_t cx_crc32_update(uint32_t crc_state, const void *buf, size_t len);
+
 #endif  // HAVE_CRC
 
 #endif  // LCX_CRC_H
diff --git a/lib_cxng/src/cx_crc.h b/lib_cxng/src/cx_crc.h
index 0698874c..bc7a811f 100644
--- a/lib_cxng/src/cx_crc.h
+++ b/lib_cxng/src/cx_crc.h
@@ -21,10 +21,7 @@
 
 #ifdef HAVE_CRC
 
-#include <stddef.h>
-#include <stdint.h>
-
-uint32_t cx_crc32(const void *buf, size_t len);
+#include "lcx_crc.h"
 
 #endif  // HAVE_CRC
 
diff --git a/lib_stusb_impl/u2f_impl.c b/lib_stusb_impl/u2f_impl.c
index a77b15f8..70a2db18 100644
--- a/lib_stusb_impl/u2f_impl.c
+++ b/lib_stusb_impl/u2f_impl.c
@@ -332,7 +332,7 @@ void u2f_handle_cmd_msg(u2f_service_t *service, uint8_t *buffer, uint16_t length
     uint8_t p2  = buffer[OFFSET_P2];
 #endif  // U2F_PROXY_MAGIC
 
-    uint32_t dataLength = u2f_get_cmd_msg_data_length(buffer, length);
+    int dataLength = u2f_get_cmd_msg_data_length(buffer, length);
     if (dataLength < 0) {
         // invalid size
         u2f_message_reply(