diff --git a/src/core/os.c b/src/core/os.c
index e6e53ca5..c686516a 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -322,9 +322,6 @@ static const JanetAbstractType ProcAT;
 #define JANET_PROC_WAITED 2
 #define JANET_PROC_WAITING 4
 #define JANET_PROC_ERROR_NONZERO 8
-#define JANET_PROC_OWNS_STDIN 16
-#define JANET_PROC_OWNS_STDOUT 32
-#define JANET_PROC_OWNS_STDERR 64
 typedef struct {
     int flags;
 #ifdef JANET_WINDOWS