Here's a patch to fix the issue:
diff --git a/src/libmawk/vio_fifo.h b/src/libmawk/vio_fifo.h index f170c22..a2d751d 100644 --- a/src/libmawk/vio_fifo.h +++ b/src/libmawk/vio_fifo.h @@ -14,7 +14,7 @@ typedef struct mawk_vio_fifo_s { int eof_from_app; /* 1 if there won't be more from the app or the app won't accept more data */ } mawk_vio_fifo_t; -const mawk_vio_imp_t mawk_vio_fifo_imp; +extern const mawk_vio_imp_t mawk_vio_fifo_imp; mawk_vio_t *mawk_vio_fifo_open(mawk_state_t *MAWK, const char *name, mawk_vio_open_mode_t mode);