diff --git a/src/core/ev.c b/src/core/ev.c
index a539b8d4..7a29fec1 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -1125,6 +1125,20 @@ void janet_ev_deinit(void) {
  * There is some networking code in here as well as generic
  * reading and writing primitives. */
 
+void janet_stream_flags(JanetStream *stream, uint32_t flags) {
+    if (stream->flags & JANET_STREAM_CLOSED) {
+        janet_panic("stream is closed");
+    }
+    if ((stream->flags & flags) != flags) {
+        const char *rmsg = "", *wmsg = "", *amsg = "", *dmsg = "", *smsg = "stream";
+        if (flags & JANET_STREAM_READABLE) rmsg = "readable ";
+        if (flags & JANET_STREAM_WRITABLE) wmsg = "writable ";
+        if (flags & JANET_STREAM_ACCEPTABLE) amsg = "server ";
+        if (flags & JANET_STREAM_UDPSERVER) dmsg = "datagram ";
+        if (flags & JANET_STREAM_SOCKET) smsg = "socket";
+        janet_panicf("bad stream, expected %s%s%s%s%s", rmsg, wmsg, amsg, dmsg, smsg);
+    }
+}
 
 /* When there is an IO error, we need to be able to convert it to a Janet
  * string to raise a Janet error. */
diff --git a/src/core/net.c b/src/core/net.c
index 4ac1cd89..f67d867c 100644
--- a/src/core/net.c
+++ b/src/core/net.c
@@ -488,18 +488,6 @@ static Janet cfun_net_listen(int32_t argc, Janet *argv) {
     }
 }
 
-void janet_stream_flags(JanetStream *stream, uint32_t flags) {
-    if ((stream->flags & flags) != flags || (stream->flags & JANET_STREAM_CLOSED)) {
-        const char *rmsg = "", *wmsg = "", *amsg = "", *dmsg = "", *smsg = "stream";
-        if (flags & JANET_STREAM_READABLE) rmsg = "readable ";
-        if (flags & JANET_STREAM_WRITABLE) wmsg = "writable ";
-        if (flags & JANET_STREAM_ACCEPTABLE) amsg = "server ";
-        if (flags & JANET_STREAM_UDPSERVER) dmsg = "datagram ";
-        if (flags & JANET_STREAM_SOCKET) smsg = "socket";
-        janet_panicf("bad stream, expected %s%s%s%s%s", rmsg, wmsg, amsg, dmsg, smsg);
-    }
-}
-
 static Janet cfun_stream_accept_loop(int32_t argc, Janet *argv) {
     janet_fixarity(argc, 2);
     JanetStream *stream = janet_getabstract(argv, 0, &janet_stream_type);
diff --git a/src/core/os.c b/src/core/os.c
index 3e1cba31..16fbe348 100644
--- a/src/core/os.c
+++ b/src/core/os.c
@@ -1661,12 +1661,6 @@ static Janet os_open(int32_t argc, Janet *argv) {
             case 'x':
                 open_flags |= O_SYNC;
                 break;
-            case 'y':
-                open_flags |= O_DSYNC;
-                break;
-            case 'z':
-                open_flags |= O_RSYNC;
-                break;
             case 'C':
                 open_flags |= O_NOCTTY;
                 break;
@@ -2023,9 +2017,7 @@ static const JanetReg os_cfuns[] = {
              "\t:t - shorten an existing file to length 0 (O_TRUNC)\n\n"
              "Posix only flags:\n"
              "\t:a - append to a file (O_APPEND)\n"
-             "\t:x - O_DSYNC\n"
-             "\t:y - O_SYNC\n"
-             "\t:z - O_RSYNC\n"
+             "\t:x - O_SYNC\n"
              "\t:C - O_NOCTTY\n\n"
              "Windows only flags:\n"
              "\t:R - share reads (FILE_SHARE_READ)\n"