diff --git a/src/core/io.c b/src/core/io.c
index abba83cf..8cdd9b74 100644
--- a/src/core/io.c
+++ b/src/core/io.c
@@ -164,6 +164,36 @@ static Janet cfun_io_fopen(int32_t argc, Janet *argv) {
     return f ? makef(f, flags) : janet_wrap_nil();
 }
 
+static Janet cfun_io_fdopen(int32_t argc, Janet *argv) {
+    janet_arity(argc, 1, 2);
+    const int fd = janet_getinteger(argv, 0);
+    const uint8_t *fmode;
+    int flags;
+    if (argc == 2) {
+        fmode = janet_getkeyword(argv, 1);
+        flags = checkflags(fmode);
+    } else {
+        fmode = (const uint8_t *)"r";
+        flags = IO_READ;
+    }
+#ifdef JANET_WINDOWS
+#define fdopen _fdopen
+#endif
+    FILE *f = fdopen(fd, (const char *)fmode);
+    return f ? makef(f, flags) : janet_wrap_nil();
+}
+
+static Janet cfun_io_fileno(int32_t argc, Janet *argv) {
+    janet_fixarity(argc, 1);
+    IOFile *iof = janet_getabstract(argv, 0, &cfun_io_filetype);
+    if (iof->flags & IO_CLOSED)
+        janet_panic("file is closed");
+#ifdef JANET_WINDOWS
+#define fileno _fileno
+#endif
+    return janet_wrap_integer(fileno(iof->file));
+}
+
 /* Read up to n bytes into buffer. */
 static void read_chunk(IOFile *iof, JanetBuffer *buffer, int32_t nBytesMax) {
     if (!(iof->flags & (IO_READ | IO_UPDATE)))
@@ -390,6 +420,26 @@ static const JanetReg io_cfuns[] = {
              "\tb - open the file in binary mode (rather than text mode)\n"
              "\t+ - append to the file instead of overwriting it")
     },
+    {
+        "file/fdopen", cfun_io_fdopen,
+        JDOC("(file/fdopen fd [,mode])\n\n"
+             "Create a file from an fd. fd is a platform specific file descriptor, and "
+             "mode is a set of flags indicating the mode to open the file in. "
+             "mode is a keyword where each character represents a flag. If the file "
+             "cannot be opened, returns nil, otherwise returns the new file handle. "
+             "Mode flags:\n\n"
+             "\tr - allow reading from the file\n"
+             "\tw - allow writing to the file\n"
+             "\ta - append to the file\n"
+             "\tb - open the file in binary mode (rather than text mode)\n"
+             "\t+ - append to the file instead of overwriting it")
+    },
+    {
+        "file/fileno", cfun_io_fileno,
+        JDOC("(file/fileno f)\n\n"
+             "Return the underlying file descriptor for the file as a number."
+             "The meaning of this number is platform specific.")
+    },
     {
         "file/close", cfun_io_fclose,
         JDOC("(file/close f)\n\n"