diff --git a/libc/fmt/fmt.c b/libc/fmt/fmt.c
index d21133f53..99b8e8afd 100644
--- a/libc/fmt/fmt.c
+++ b/libc/fmt/fmt.c
@@ -359,10 +359,15 @@ _Hide int __fmt(void *fn, void *arg, const char *format, va_list va) {
           p = "\r\e[K";
           goto FormatString;
         }
+      case 'S':
+        // Specified by POSIX to be equivalent to %ls
+        signbit = 63;
+        goto FormatStringPNotFetchedYet;
       case 'q':
         flags |= FLAGS_QUOTE;
         // fallthrough
       case 's':
+      FormatStringPNotFetchedYet:
         p = va_arg(va, void *);
       FormatString:
         if (__fmt_stoa(out, arg, p, flags, prec, width, signbit, qchar) == -1) {
diff --git a/test/libc/fmt/fmt_test.c b/test/libc/fmt/fmt_test.c
index 68fc3f545..0b8ee2989 100644
--- a/test/libc/fmt/fmt_test.c
+++ b/test/libc/fmt/fmt_test.c
@@ -64,6 +64,10 @@ TEST(fmt, d) {
   EXPECT_STREQ("-2147483648", _gc(xasprintf("% d", INT_MIN)));
 }
 
+TEST(fmt, s) {
+  EXPECT_STREQ("Wide character output test", _gc(xasprintf("%S", L"Wide character output test")));
+}
+
 TEST(fmt, g) {
   EXPECT_STREQ("1", _gc(xasprintf("%g", 1.)));
   EXPECT_STREQ(" 1", _gc(xasprintf("% g", 1.)));