diff --git a/racket/src/rktio/configure b/racket/src/rktio/configure
index d926a2bdfd..f3754c97df 100755
--- a/racket/src/rktio/configure
+++ b/racket/src/rktio/configure
@@ -3036,6 +3036,11 @@ ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
+# If using gcc, we want all warnings:
+if test "$CC" = "gcc" ; then
+  CFLAGS="$CFLAGS -Wall"
+fi
+
 if test -n "$ac_tool_prefix"; then
   # Extract the first word of "${ac_tool_prefix}ranlib", so it can be a program name with args.
 set dummy ${ac_tool_prefix}ranlib; ac_word=$2
@@ -4188,11 +4193,11 @@ if test "${enable_shared}" = "yes" ; then
     fi
   fi
 
-  AR="${LIBTOOLPROG} --mode=link --tag=CC $CC${need_gcc_static_libgcc}${ar_libtool_no_undefined} -release ${plt_lib_version} -rpath ${abslibdir} \$(ARLIBFLAGS) -o"
+  AR="${LIBTOOLPROG} --mode=link --tag=CC $CC${need_gcc_static_libgcc}${ar_libtool_no_undefined} -release ${plt_lib_version} \$(ARLIBFLAGS) -o"
   STATIC_AR="${LIBTOOLPROG} --mode=link --tag=CC $CC -o"
   ARFLAGS=""
   RANLIB=":"
-  RKTLINKER="${LIBTOOLPROG} --mode=link --tag=CC $CC${need_gcc_static_libgcc} -rpath ${abslibdir}"
+  RKTLINKER="${LIBTOOLPROG} --mode=link --tag=CC $CC${need_gcc_static_libgcc}"
   CC="${LIBTOOLPROG} --mode=compile --tag=CC $CC"
   LIBSFX=la
   LTO="lo"
diff --git a/racket/src/rktio/configure.ac b/racket/src/rktio/configure.ac
index b246bbe41a..c469850b72 100644
--- a/racket/src/rktio/configure.ac
+++ b/racket/src/rktio/configure.ac
@@ -16,6 +16,11 @@ AC_ARG_ENABLE(shared,  [  --enable-shared         create shared libraries (ok, b
 
 AC_PROG_CC
 
+# If using gcc, we want all warnings:
+if test "$CC" = "gcc" ; then 
+  CFLAGS="$CFLAGS -Wall"
+fi
+
 AC_PROG_RANLIB
 if test "$AR" = '' ; then 
   AR="${ac_tool_prefix}ar"
diff --git a/racket/src/rktio/rktio.h b/racket/src/rktio/rktio.h
index 76ac82f27c..a18689ba26 100644
--- a/racket/src/rktio/rktio.h
+++ b/racket/src/rktio/rktio.h
@@ -242,7 +242,7 @@ void rktio_poll_add_fs_change(rktio_t *rktio, rktio_fs_change_t *fc, rktio_poll_
 void rktio_poll_set_add_nosleep(rktio_t *rktio, rktio_poll_set_t *fds);
 
 #ifdef RKTIO_SYSTEM_WINDOWS
-void rktio_poll_set_add_handle(rktio_t *rktio, HANDLE h, rktio_poll_set_t *fds, int repost);
+void rktio_poll_set_add_handle(rktio_t *rktio, intptr_t h, rktio_poll_set_t *fds, int repost);
 void rktio_poll_set_add_eventmask(rktio_t *rktio, rktio_poll_set_t *fds, int mask);
 #endif
 
diff --git a/racket/src/rktio/rktio_config.h.in b/racket/src/rktio/rktio_config.h.in
index a2a0699996..76108094a4 100644
--- a/racket/src/rktio/rktio_config.h.in
+++ b/racket/src/rktio/rktio_config.h.in
@@ -1,3 +1,10 @@
+#if ((defined(_MSC_VER) || defined(__MINGW32__))                        \
+     && (defined(__WIN32__) || defined(WIN32) || defined(_WIN32)))
+# define RKTIO_SYSTEM_WINDOWS
+#else
+# define RKTIO_SYSTEM_UNIX
+#endif
+
 /* Whether `intptr_t' is available. */
 #undef HAVE_INTPTR_T
 
diff --git a/racket/src/rktio/rktio_fd.c b/racket/src/rktio/rktio_fd.c
index b44f477ef8..4d8935f43e 100644
--- a/racket/src/rktio/rktio_fd.c
+++ b/racket/src/rktio/rktio_fd.c
@@ -66,13 +66,13 @@ typedef struct Win_FD_Output_Thread {
 		       works. We still use a thread to detect when the
 		       write has ben flushed, which in turn is needed to
 		       know whether future writes will immediately succeed. */
-  volatile flushed, needflush; /* Used for non-blocking, only. The flushed
-				  flag communicates from the flush-testing thread
-				  to the main thread. For efficiency, we request
-				  flush checking only when needed (instead of
-				  after every write); needflush indicates that
-				  a flush check is currently needed, but hasn't
-				  been started. */
+  volatile int flushed, needflush; /* Used for non-blocking, only. The flushed
+                                      flag communicates from the flush-testing thread
+                                      to the main thread. For efficiency, we request
+                                      flush checking only when needed (instead of
+                                      after every write); needflush indicates that
+                                      a flush check is currently needed, but hasn't
+                                      been started. */
   volatile int done, err_no;
   volatile unsigned int buflen, bufstart, bufend; /* used for blocking, only */
   unsigned char *buffer; /* used for blocking, only */
@@ -147,7 +147,7 @@ static void init_read_fd(rktio_t *rktio, rktio_fd_t *rfd)
     /* Replace buffer with a malloced one: */
     bfr = malloc(RKTIO_FD_BUFFSIZE);
     rfd->buffer = bfr;
-    th->buffer = bfr;
+    th->buffer = (unsigned char *)bfr;
 
     th->fd = rfd->fd;
     th->avail = 0;
@@ -286,8 +286,6 @@ void rktio_reliably_close(intptr_t s) {
 int rktio_close(rktio_t *rktio, rktio_fd_t *rfd)
 {
 #ifdef RKTIO_SYSTEM_UNIX
-  int cr;
-  
 # ifdef USE_FCNTL_AND_FORK_FOR_FILE_LOCKS
   if (!(rfd->modes & RKTIO_OPEN_SOCKET))
     release_lockf(rfd->fd);
@@ -613,28 +611,28 @@ void rktio_poll_add(rktio_t *rktio, rktio_fd_t *rfd, rktio_poll_set_t *fds, int
           if (rfd->th->avail || rfd->th->err || rfd->th->eof) {
             /* Data is ready. We shouldn't be trying to sleep, so force an
                immediate wake-up: */
-            rktio_fdset_add_nosleep(fds);
+            rktio_poll_set_add_nosleep(rktio, fds);
           } else {
             rfd->th->checking = 1;
             ReleaseSemaphore(rfd->th->checking_sema, 1, NULL);
-            rktio_fdset_add_handle(rfd->th->ready_sema, fds, 1);
+            rktio_poll_set_add_handle(rktio, (intptr_t)rfd->th->ready_sema, fds, 1);
           }
         } else
-          rktio_fdset_add_handle(rfd->th->ready_sema, fds, 1);
+          rktio_poll_set_add_handle(rktio, (intptr_t)rfd->th->ready_sema, fds, 1);
       } else if (rktio_fd_is_regular_file(rktio, rfd)) {
         /* regular files never block */
-        rktio_fdset_add_nosleep(fds);
+        rktio_poll_set_add_nosleep(rktio, fds);
       } else {
         /* This case is not currently used. See fd_byte_ready. */
-        rktio_fdset_add_handle(rfd->fd, fds, 0);
+        rktio_poll_set_add_handle(rktio, (intptr_t)rfd->fd, fds, 0);
       }
     }
 
     if (modes & RKTIO_POLL_WRITE) {
       if (rfd->oth && !rktio_poll_write_ready(rktio, rfd))
-        rktio_poll_set_add_handle(rfd->oth->ready_sema, fds, 1);
+        rktio_poll_set_add_handle(rktio, (intptr_t)rfd->oth->ready_sema, fds, 1);
       else
-        rktio_poll_set_nosleep(fds);
+        rktio_poll_set_nosleep(rktio, fds);
     }
   }
 #endif
diff --git a/racket/src/rktio/rktio_fs.c b/racket/src/rktio/rktio_fs.c
index a2b327f83d..34065ccd67 100644
--- a/racket/src/rktio/rktio_fs.c
+++ b/racket/src/rktio/rktio_fs.c
@@ -9,12 +9,13 @@
 #include <stdlib.h>
 #ifdef RKTIO_SYSTEM_UNIX
 # include <fcntl.h>
-#include <pwd.h>
-#include <grp.h>
-#include <dirent.h>
+# include <pwd.h>
+# include <grp.h>
+# include <dirent.h>
 #endif
 #ifdef RKTIO_SYSTEM_WINDOWS
 # include <shlobj.h>
+# include <direct.h>
 #endif
 
 #ifdef RKTIO_SYSTEM_UNIX
@@ -108,6 +109,10 @@ static void init_procs()
 # define GET_FF_MODDATE(fd) convert_date(&fd.ftLastWriteTime)
 # define GET_FF_NAME(fd) fd.cFileName
 
+# define MKDIR_NO_MODE_FLAG
+
+#define is_drive_letter(c) (((unsigned char)c < 128) && isalpha((unsigned char)c))
+
 static time_t convert_date(const FILETIME *ft)
 {
   LONGLONG l, delta;
@@ -418,7 +423,7 @@ static int UNC_stat(rktio_t *rktio, const char *dirname, int *flags, int *isdir,
           if (dest) free(dest);
           dest_len = len + 1;
           dest = malloc(dest_len);
-          len = GetFinalPathNameByHandleProcW(h, dest, dest_len, rktioFILE_NAME_NORMALIZED);
+          len = GetFinalPathNameByHandleProc(h, dest, dest_len, rktioFILE_NAME_NORMALIZED);
         } while (len > dest_len);
 
         if (!len) {
@@ -756,9 +761,8 @@ static int enable_write_permission(rktio_t *rktio, const char *fn)
 
 int rktio_delete_file(rktio_t *rktio, char *fn, int enable_write_on_fail)
 {
-  int errid;
-
 #ifdef RKTIO_SYSTEM_WINDOWS
+  int errid;
   if (DeleteFileW(WIDE_PATH_temp(fn)))
     return 1;
   errid = GetLastError();
@@ -803,7 +807,6 @@ int rktio_rename_file(rktio_t *rktio, char *dest, char *src, int exists_ok)
     /* Then we have the great misfortune of running in Windows 9x. If
        exists_ok, then do something no less stupid than the OS
        itself: */
-    int errid;
     if (exists_ok)
       MSC_W_IZE(unlink)(MSC_WIDE_PATH_temp(dest));
     if (MoveFileW(src_w, WIDE_PATH_temp(dest))) {
@@ -878,7 +881,6 @@ int rktio_make_directory(rktio_t *rktio, char *filename)
   set_racket_error(RKTIO_ERROR_UNSUPPORTED);
   return 0;
 #else
-  int exists_already = 0;
   int len, copied = 0;
 
   /* Make sure path doesn't have trailing separator: */
@@ -1226,7 +1228,6 @@ int rktio_set_file_or_directory_permissions(rktio_t *rktio, char *filename, int
 #  endif  
 #  ifdef RKTIO_SYSTEM_WINDOWS
   {
-    int len = strlen(filename);
     int ALWAYS_SET_BITS = ((RKTIO_UNC_READ | RKTIO_UNC_EXEC)
                            | ((RKTIO_UNC_READ | RKTIO_UNC_EXEC) << 3)
                            | ((RKTIO_UNC_READ | RKTIO_UNC_EXEC) << 6));
@@ -1314,7 +1315,6 @@ rktio_directory_list_t *rktio_directory_list_start(rktio_t *rktio, char *filenam
  retry:
 
   {
-    char *nf;
     int is_ssq = 0, is_unc = 0, d, nd;
     len = strlen(filename);
     pattern = malloc(len + 14);
@@ -1347,7 +1347,7 @@ rktio_directory_list_t *rktio_directory_list_start(rktio_t *rktio, char *filenam
 	nd = 0;
       }
     }
-    memcpy(pattern + d, nf + nd, len - nd);
+    memcpy(pattern + d, filename + nd, len - nd);
     len += (d - nd);
     if (len && !IS_A_DOS_SEP(pattern[len - 1]))
       pattern[len++] = '\\';      
@@ -1410,7 +1410,6 @@ rktio_directory_list_t *rktio_directory_list_start(rktio_t *rktio, char *filenam
 {
   rktio_directory_list_t *dl;
   DIR *dir;
-  int nlen;
 
   dir = opendir(filename ? filename : ".");
   if (!dir) {
@@ -1633,7 +1632,7 @@ char **rktio_filesystem_root_list(rktio_t *rktio)
       if (GetDiskFreeSpace(s + ds, &a, &b, &c, &d)) {
         if ((ss_count + 1) == ss_len) {
           new_ss = malloc(sizeof(char*) * ss_len * 2);
-          mempcy(ss, new_ss, ss_count * sizeof(char*));
+          memcpy(ss, new_ss, ss_count * sizeof(char*));
           ss = new_ss;
           ss_len *= 2;
         }
@@ -1793,7 +1792,7 @@ char *rktio_system_path(rktio_t *rktio, int which)
   
   {
     /* Everything else is in ~: */
-    char *home_str, *ex_home, *alt_home, *home;
+    char *home_str, *alt_home, *home;
 
     if ((which == RKTIO_PATH_PREF_DIR) 
 	|| (which == RKTIO_PATH_PREF_FILE)
@@ -1905,7 +1904,7 @@ char *rktio_system_path(rktio_t *rktio, int which)
       }
 
       if (SHGetSpecialFolderLocation(NULL, which_folder, &items) == S_OK) {
-	int ok;
+        int ok;
 	IMalloc *mi;
 	wchar_t *buf;
 
@@ -1916,7 +1915,8 @@ char *rktio_system_path(rktio_t *rktio, int which)
 	mi->lpVtbl->Free(mi, items);
 	mi->lpVtbl->Release(mi);
 
-        home = NARROW_PATH_copy_then_free(buf);
+        if (ok)
+          home = NARROW_PATH_copy_then_free(buf);
       }
     }
 
@@ -1961,7 +1961,7 @@ char *rktio_system_path(rktio_t *rktio, int which)
 	
 	  s = name;
 	
-	  i = wc_strlen(s) - 1;
+	  i = wcslen(s) - 1;
 	
 	  while (i && (s[i] != '\\')) {
 	    --i;
diff --git a/racket/src/rktio/rktio_fs_change.c b/racket/src/rktio/rktio_fs_change.c
index bde7db51c2..924a7d62db 100644
--- a/racket/src/rktio/rktio_fs_change.c
+++ b/racket/src/rktio/rktio_fs_change.c
@@ -69,7 +69,6 @@ rktio_fs_change_t *rktio_fs_change(rktio_t *rktio, char *path)
 {
   int ok = 0;
 #ifndef NO_FILESYSTEM_CHANGE_EVTS
-  int errid = 0;
 # if defined(HAVE_KQUEUE_SYSCALL)
   rktio_ltps_t *lt;
   rktio_ltps_handle_t *lth;
@@ -219,7 +218,7 @@ void rktio_poll_add_fs_change(rktio_t *rktio, rktio_fs_change_t *fc, rktio_poll_
 
 #if defined(NO_FILESYSTEM_CHANGE_EVTS)
 #elif defined(RKTIO_SYSTEM_WINDOWS)
-  rktio_poll_set_add_handle(rktio, (HANDLE)fc->fd, fds, 0);
+  rktio_poll_set_add_handle(rktio, fc->fd, fds, 0);
 #elif defined(HAVE_INOTIFY_SYSCALL)
   int fd;
   fd = do_inotify_fd(rktio);
diff --git a/racket/src/rktio/rktio_ltps.c b/racket/src/rktio/rktio_ltps.c
index 28cae8b332..e12ee259ee 100644
--- a/racket/src/rktio/rktio_ltps.c
+++ b/racket/src/rktio/rktio_ltps.c
@@ -47,10 +47,13 @@ typedef struct rktio_ltps_handle_pair_t {
 static rktio_ltps_handle_pair_t *ltps_hash_get(rktio_ltps_t *lt, intptr_t fd);
 static void ltps_hash_set(rktio_ltps_t *lt, intptr_t fd, rktio_ltps_handle_pair_t *v);
 static void ltps_hash_remove(rktio_ltps_t *lt, intptr_t fd);
-static int ltps_is_hash_empty(rktio_ltps_t *lt);
 static void ltps_hash_init(rktio_ltps_t *lt);
 static void ltps_hash_free(rktio_ltps_t *lt);
 
+#if !defined(HAVE_KQUEUE_SYSCALL) && !defined(HAVE_EPOLL_SYSCALL)
+static int ltps_is_hash_empty(rktio_ltps_t *lt);
+#endif
+
 /*========================================================================*/
 
 rktio_ltps_handle_pair_t *make_ltps_handle_pair()
@@ -363,7 +366,8 @@ rktio_ltps_handle_t *rktio_ltps_add(rktio_t *rktio, rktio_ltps_t *lt, rktio_fd_t
       } else
         s = NULL;
     }
-  }
+  } else
+    s = NULL;
 
   return s;
 #endif
@@ -710,11 +714,6 @@ static void ltps_hash_set(rktio_ltps_t *lt, intptr_t fd, rktio_ltps_handle_pair_
   }
 }
 
-static int ltps_is_hash_empty(rktio_ltps_t *lt)
-{
-  return (lt->count == 0);
-}
-
 static void ltps_hash_init(rktio_ltps_t *lt)
 {
   lt->buckets = NULL;
@@ -735,3 +734,10 @@ static void ltps_hash_free(rktio_ltps_t *lt)
     free(lt->buckets);
   }
 }
+
+#if !defined(HAVE_KQUEUE_SYSCALL) && !defined(HAVE_EPOLL_SYSCALL)
+static int ltps_is_hash_empty(rktio_ltps_t *lt)
+{
+  return (lt->count == 0);
+}
+#endif
diff --git a/racket/src/rktio/rktio_network.c b/racket/src/rktio/rktio_network.c
index d0e3b70d91..69fdc38f57 100644
--- a/racket/src/rktio/rktio_network.c
+++ b/racket/src/rktio/rktio_network.c
@@ -602,7 +602,7 @@ void rktio_poll_add_addrinfo_lookup(rktio_t *rktio, rktio_addrinfo_lookup_t *loo
   ghbn_unlock(rktio);
 
 # ifdef RKTIO_SYSTEM_WINDOWS
-  rktio_poll_set_add_handle(lookup->done_sema, fds, 1);
+  rktio_poll_set_add_handle(rktio, (intptr_t)lookup->done_sema, fds, 1);
 # else
   {
     rktio_poll_set_t *fds2;
@@ -704,7 +704,6 @@ rktio_addrinfo_lookup_t *rktio_start_addrinfo_lookup(rktio_t *rktio,
 {
   rktio_addrinfo_lookup_t *lookup;
   char buf[32], *service;
-  int err;
   struct rktio_addrinfo_t *hints;
 
   if (portno >= 0) {
@@ -1109,7 +1108,6 @@ static rktio_connect_t *try_connect(rktio_t *rktio, rktio_connect_t *conn);
 rktio_connect_t *rktio_start_connect(rktio_t *rktio, rktio_addrinfo_t *dest, rktio_addrinfo_t *src)
 {
   rktio_connect_t *conn;
-  int errid;
 
 #ifdef USE_TCP
   TCP_INIT("tcp-connect");
@@ -1266,13 +1264,9 @@ static int get_no_portno(rktio_t *rktio, rktio_socket_t socket);
 
 rktio_listener_t *rktio_listen(rktio_t *rktio, rktio_addrinfo_t *src, int backlog, int reuse)
 {
-#ifdef RKTIO_TCP_LISTEN_IPV6_ONLY_SOCKOPT
-  int no_ipv6 = 0;
-#endif
-    
   {
     rktio_addrinfo_t *addr;
-    int err, count = 0, pos = 0, i;
+    int count = 0, pos = 0;
     rktio_listener_t *l = NULL;
 #ifdef RKTIO_TCP_LISTEN_IPV6_ONLY_SOCKOPT
     int any_v4 = 0, any_v6 = 0;
@@ -1564,7 +1558,8 @@ void rktio_poll_add_receive(rktio_t *rktio, rktio_listener_t *listener, rktio_po
 
 rktio_fd_t *rktio_accept(rktio_t *rktio, rktio_listener_t *listener)
 {
-  int was_closed = 0, errid, ready_pos;
+  int
+    ready_pos;
   rktio_socket_t s, ls;
   unsigned int l;
   char tcp_accept_addr[RKTIO_SOCK_NAME_MAX_LEN];
@@ -1958,6 +1953,8 @@ int rktio_udp_change_multicast_group(rktio_t *rktio, rktio_fd_t *rfd,
     optname = IP_ADD_MEMBERSHIP;
   else if (action == RKTIO_DROP_MEMBERSHIP)
     optname = IP_DROP_MEMBERSHIP;
+  else
+    optname = 0;
 
   status = setsockopt(s, IPPROTO_IP, optname, (void *) &mreq, mreq_len);
   
diff --git a/racket/src/rktio/rktio_poll_set.c b/racket/src/rktio/rktio_poll_set.c
index ba481c38d0..289ddb198d 100644
--- a/racket/src/rktio/rktio_poll_set.c
+++ b/racket/src/rktio/rktio_poll_set.c
@@ -525,8 +525,9 @@ int rktio_get_fd_limit(rktio_poll_set_t *fds)
   return 0;
 }
 
-void rktio_poll_set_add_handle(HANDLE h, rktio_poll_set_t *fds, int repost)
+void rktio_poll_set_add_handle(rktio_t *rktio, intptr_t _h, rktio_poll_set_t *fds, int repost)
 {
+  HANDLE h = (HANDLE)_h;
   rktio_poll_set_t *efd = fds;
   HANDLE *hs;
   int i, new_i, *rps;
diff --git a/racket/src/rktio/rktio_private.h b/racket/src/rktio/rktio_private.h
index 6a4360ef47..a563783128 100644
--- a/racket/src/rktio/rktio_private.h
+++ b/racket/src/rktio/rktio_private.h
@@ -1,10 +1,3 @@
-#if ((defined(_MSC_VER) || defined(__MINGW32__))                        \
-     && (defined(__WIN32__) || defined(WIN32) || defined(_WIN32)))
-# define RKTIO_SYSTEM_WINDOWS
-#else
-# define RKTIO_SYSTEM_UNIX
-#endif
-
 #if defined(__APPLE__) && defined(__MACH__) && !defined(OS_X)
 # define OS_X
 #endif
diff --git a/racket/src/rktio/rktio_process.c b/racket/src/rktio/rktio_process.c
index 9b59f8ba09..b02ced0dc7 100644
--- a/racket/src/rktio/rktio_process.c
+++ b/racket/src/rktio/rktio_process.c
@@ -830,7 +830,7 @@ void rktio_poll_add_process(rktio_t *rktio, rktio_process_t *sp, rktio_poll_set_
   }
   
 #ifdef RKTIO_SYSTEM_WINDOWS
-  rktio_poll_set_add_handle(rktio, sp->handle, fds, 0);
+  rktio_poll_set_add_handle(rktio, (intptr_t)sp->handle, fds, 0);
 #endif
 }
 
@@ -1239,12 +1239,11 @@ rktio_process_result_t *rktio_process(rktio_t *rktio,
 {
   rktio_process_result_t *result;
   intptr_t to_subprocess[2], from_subprocess[2], err_subprocess[2];
-  int i, pid, errid;
+  int pid, errid;
 #if defined(RKTIO_SYSTEM_UNIX)
 # if !defined(CENTRALIZED_SIGCHILD)
   System_Child *sc;
 # endif
-  int fork_errno = 0;
 #else
   void *sc = 0;
 #endif
@@ -1255,9 +1254,12 @@ rktio_process_result_t *rktio_process(rktio_t *rktio,
 #endif
   int new_process_group = (flags & RKTIO_PROCESS_NEW_GROUP);
   int stderr_is_stdout = (flags & RKTIO_PROCESS_STDOUT_AS_STDERR);
+#if defined(RKTIO_SYSTEM_WINDOWS)
   int windows_exact_cmdline = (flags & RKTIO_PROCESS_WINDOWS_EXACT_CMDLINE);
   int windows_chain_termination_to_child = (flags & RKTIO_PROCESS_WINDOWS_CHAIN_TERMINATION);
-
+  int i;
+#endif
+  
   /* avoid compiler warnings: */
   to_subprocess[0] = -1;
   to_subprocess[1] = -1;
diff --git a/racket/src/rktio/rktio_wide.c b/racket/src/rktio/rktio_wide.c
index ccdaa37d32..71e9b8b5b6 100644
--- a/racket/src/rktio/rktio_wide.c
+++ b/racket/src/rktio/rktio_wide.c
@@ -312,7 +312,7 @@ char *rktio_convert_from_wchar(const wchar_t *ws, int free_given)
   intptr_t len, l;
   char *s;
 
-  l = wc_slen(ws) + 1; /* add nul terminator */
+  l = wcslen(ws) + 1; /* add nul terminator */
 
   len = utf16ish_to_utf8ish((unsigned short *)ws, l, NULL);