diff --git a/ap/libc/glibc/glibc-2.23/stdlib/testmb.c b/ap/libc/glibc/glibc-2.23/stdlib/testmb.c
new file mode 100644
index 0000000..45dae7d
--- /dev/null
+++ b/ap/libc/glibc/glibc-2.23/stdlib/testmb.c
@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int
+main (int argc, char *argv[])
+{
+  wchar_t w[10];
+  char c[10];
+  int i;
+  int lose = 0;
+
+  i = mbstowcs (w, "bar", 4);
+  if (!(i == 3 && w[1] == 'a'))
+    {
+      puts ("mbstowcs FAILED!");
+      lose = 1;
+    }
+
+  mbstowcs (w, "blah", 5);
+  i = wcstombs (c, w, 10);
+  if (i != 4)
+    {
+      puts ("wcstombs FAILED!");
+      lose = 1;
+    }
+
+  if (mblen ("foobar", 7) != 1)
+    {
+      puts ("mblen 1 FAILED!");
+      lose = 1;
+    }
+
+  if (mblen ("", 1) != 0)
+    {
+      puts ("mblen 2 FAILED!");
+      lose = 1;
+    }
+
+  {
+    int r;
+    char c = 'x';
+    wchar_t wc;
+    char mbc[MB_CUR_MAX];
+
+    if ((r = mbtowc (&wc, &c, MB_CUR_MAX)) <= 0)
+      {
+	printf ("conversion to wide failed, result: %d\n", r);
+	lose = 1;
+      }
+    else
+      {
+	printf ("wide value: 0x%04lx\n", (unsigned long) wc);
+	mbc[0] = '\0';
+	if ((r = wctomb (mbc, wc)) <= 0)
+	  {
+	    printf ("conversion to multibyte failed, result: %d\n", r);
+	    lose = 1;
+	  }
+      }
+
+  }
+
+  puts (lose ? "Test FAILED!" : "Test succeeded.");
+  return lose;
+}