diff --git a/src/mfoc.h b/src/mfoc.h
index 9ea7547..c026aa9 100644
--- a/src/mfoc.h
+++ b/src/mfoc.h
@@ -82,7 +82,7 @@ typedef struct {
 } countKeys;
 
 
-void usage(FILE *stream, int errno);
+void usage(FILE *stream, int code);
 void mf_init(mfreader *r);
 void mf_configure(nfc_device *pdi);
 void mf_select_tag(nfc_device *pdi, nfc_target *pnt);