diff --git a/mysys/string.c b/mysys/string.c
index d9791341c60..06fd2c3d014 100644
--- a/mysys/string.c
+++ b/mysys/string.c
@@ -142,16 +142,14 @@ my_bool dynstr_trunc(DYNAMIC_STRING *str, size_t n)
 my_bool dynstr_append_os_quoted(DYNAMIC_STRING *str, const char *append, ...)
 {
 #ifdef __WIN__
-  const char *quote_str= "\"";
-  const uint  quote_len= 1;
+  LEX_CSTRING quote= { C_STRING_WITH_LEN("\"") };
 #else
-  const char *quote_str= "\'";
-  const uint  quote_len= 1;
+  LEX_CSTRING quote= { C_STRING_WITH_LEN("\'") };
 #endif /* __WIN__ */
   my_bool ret= TRUE;
   va_list dirty_text;
 
-  ret&= dynstr_append_mem(str, quote_str, quote_len); /* Leading quote */
+  ret&= dynstr_append_mem(str, quote.str, quote.length); /* Leading quote */
   va_start(dirty_text, append);
   while (append != NullS)
   {
@@ -159,18 +157,18 @@ my_bool dynstr_append_os_quoted(DYNAMIC_STRING *str, const char *append, ...)
     const char *next_pos= cur_pos;
 
     /* Search for quote in each string and replace with escaped quote */
-    while(*(next_pos= strcend(cur_pos, quote_str[0])) != '\0')
+    while(*(next_pos= strcend(cur_pos, quote.str[0])) != '\0')
     {
       ret&= dynstr_append_mem(str, cur_pos, (uint) (next_pos - cur_pos));
-      ret&= dynstr_append_mem(str ,"\\", 1);
-      ret&= dynstr_append_mem(str, quote_str, quote_len);
+      ret&= dynstr_append_mem(str, STRING_WITH_LEN("\\"));
+      ret&= dynstr_append_mem(str, quote.str, quote.length);
       cur_pos= next_pos + 1;
     }
     ret&= dynstr_append_mem(str, cur_pos, (uint) (next_pos - cur_pos));
     append= va_arg(dirty_text, char *);
   }
   va_end(dirty_text);
-  ret&= dynstr_append_mem(str, quote_str, quote_len); /* Trailing quote */
+  ret&= dynstr_append_mem(str, quote.str, quote.length); /* Trailing quote */
 
   return ret;
 }
diff --git a/unittest/mysys/CMakeLists.txt b/unittest/mysys/CMakeLists.txt
index c4af7828e42..5a46efc8e5a 100644
--- a/unittest/mysys/CMakeLists.txt
+++ b/unittest/mysys/CMakeLists.txt
@@ -14,7 +14,7 @@
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 
 MY_ADD_TESTS(bitmap base64 my_vsnprintf my_atomic my_rdtsc lf my_malloc
-             my_getopt
+             my_getopt dynstring
              LINK_LIBRARIES mysys)
 
 IF(WIN32)
diff --git a/unittest/mysys/dynstring-t.c b/unittest/mysys/dynstring-t.c
new file mode 100644
index 00000000000..ca78e45d30c
--- /dev/null
+++ b/unittest/mysys/dynstring-t.c
@@ -0,0 +1,74 @@
+/* Copyright (c) 2016, MariaDB
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+
+//#include <my_global.h>
+#include <m_string.h>
+#include <my_sys.h>
+#include <tap.h>
+
+DYNAMIC_STRING str1;
+
+static void check(const char *res)
+{
+  ok(strcmp(str1.str, res) == 0, "strcmp: %s", str1.str);
+  str1.length= 0;
+}
+
+int main(void)
+{
+  plan(23);
+
+  IF_WIN(skip_all("Test of POSIX shell escaping rules, not for CMD.EXE\n"), );
+
+  ok(init_dynamic_string(&str1, NULL, 0, 32) == 0, "init");
+
+  ok(dynstr_append_os_quoted(&str1, "test1", NULL) == 0, "append");
+  check("'test1'");
+
+  ok(dynstr_append_os_quoted(&str1, "con", "cat", NULL) == 0, "append");
+  check("'concat'");
+
+  ok(dynstr_append_os_quoted(&str1, "", NULL) == 0, "append");
+  check("''");
+
+  ok(dynstr_append_os_quoted(&str1, "space inside", NULL) == 0, "append");
+  check("'space inside'");
+
+  ok(dynstr_append_os_quoted(&str1, "single'quote", NULL) == 0, "append");
+  check("'single\\'quote'");
+
+  ok(dynstr_append_os_quoted(&str1, "many'single'quotes", NULL) == 0, "append");
+  check("'many\\'single\\'quotes'");
+
+  ok(dynstr_append_os_quoted(&str1, "'single quoted'", NULL) == 0, "append");
+  check("'\\'single quoted\\''");
+
+  ok(dynstr_append_os_quoted(&str1, "double\"quote", NULL) == 0, "append");
+  check("'double\"quote'");
+
+  ok(dynstr_append_os_quoted(&str1, "mixed\"single'and\"double'quotes", NULL) == 0, "append");
+  check("'mixed\"single\\'and\"double\\'quotes'");
+
+  ok(dynstr_append_os_quoted(&str1, "back\\space", NULL) == 0, "append");
+  check("'back\\space'");
+
+  ok(dynstr_append_os_quoted(&str1, "backspace\\'and\\\"quote", NULL) == 0, "append");
+  check("'backspace\\\\'and\\\"quote'");
+
+  dynstr_free(&str1);
+
+  return exit_status();
+}
+