diff --git a/options.c b/options.c
index 1117a0a7..77089956 100644
--- a/options.c
+++ b/options.c
@@ -766,11 +766,23 @@ init_options (struct options *o, const bool init_gc)
 #ifdef ENABLE_X509ALTUSERNAME
   o->x509_username_field = X509_USERNAME_FIELD_DEFAULT;
 #endif
-#endif
-#endif
+#endif /* USE_SSL */
+#endif /* USE_CRYPTO */
 #ifdef ENABLE_PKCS11
   o->pkcs11_pin_cache_period = -1;
 #endif			/* ENABLE_PKCS11 */
+
+  /* Set default --tmp-dir */
+#ifdef WIN32
+  /* On Windows, find temp dir via enviroment variables */
+  o->tmp_dir = win_get_tempdir();
+#else
+  /* Non-windows platforms use $TMPDIR, and if not set, default to '/tmp' */
+  o->tmp_dir = getenv("TMPDIR");
+  if( !o->tmp_dir ) {
+          o->tmp_dir = "/tmp";
+  }
+#endif /* WIN32 */
 }
 
 void
@@ -1916,8 +1928,6 @@ options_postprocess_verify_ce (const struct options *options, const struct conne
 	msg (M_USAGE, "--client-connect requires --mode server");
       if (options->client_disconnect_script)
 	msg (M_USAGE, "--client-disconnect requires --mode server");
-      if (options->tmp_dir)
-	msg (M_USAGE, "--tmp-dir requires --mode server");
       if (options->client_config_dir || options->ccd_exclusive)
 	msg (M_USAGE, "--client-config-dir/--ccd-exclusive requires --mode server");
       if (options->enable_c2c)
diff --git a/win32.c b/win32.c
index 7c9901e0..2b7bf7b3 100644
--- a/win32.c
+++ b/win32.c
@@ -1093,4 +1093,23 @@ env_set_add_win32 (struct env_set *es)
   set_win_sys_path (DEFAULT_WIN_SYS_PATH, es);
 }
 
+
+const char *
+win_get_tempdir()
+{
+  static char buf[MAX_PATH];
+  char *tmpdir = buf;
+
+  CLEAR(buf);
+
+  if (!GetTempPath(sizeof(buf),buf)) {
+    /* Warn if we can't find a valid temporary directory, which should
+     * be unlikely.
+     */
+    msg (M_WARN, "Could not find a suitable temporary directory."
+         " (GetTempPath() failed).  Consider to use --tmp-dir");
+    tmpdir = NULL;
+  }
+  return tmpdir;
+}
 #endif
diff --git a/win32.h b/win32.h
index fcc3062d..b6a162ea 100644
--- a/win32.h
+++ b/win32.h
@@ -270,5 +270,8 @@ char *get_win_sys_path (void);
 /* call self in a subprocess */
 void fork_to_self (const char *cmdline);
 
+/* Find temporary directory */
+const char *win_get_tempdir();
+
 #endif
 #endif