diff --git a/configure.ac b/configure.ac
index f941c14..8f2a64f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -14,7 +14,7 @@ AC_PATH_PROG(PKG_CONFIG, pkg-config)
 # Checks for header files.
 AC_HEADER_STDC
 AC_HEADER_STDBOOL
-AC_CHECK_HEADERS([stdio.h stdlib.h stdint.h stddef.h stdbool.h])
+AC_CHECK_HEADERS([stdio.h stdlib.h stdint.h stddef.h stdbool.h usb.h])
 
 # Checks for types
 AC_TYPE_SIZE_T
diff --git a/src/libnfc.h b/src/libnfc.h
index b191908..39e4393 100644
--- a/src/libnfc.h
+++ b/src/libnfc.h
@@ -29,7 +29,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "bitutils.h"
 #include "devices.h"
 
-dev_info* nfc_connect();
+dev_info* nfc_connect(void);
 void nfc_disconnect(dev_info* pdi);
 bool nfc_configure(dev_info* pdi, const dev_config_option dco, const bool bEnable);