diff --git a/build.json b/build.json
index 170b148..579ede3 100644
--- a/build.json
+++ b/build.json
@@ -231,6 +231,7 @@
         "src/core/support/file.h",
         "src/core/support/murmur_hash.h",
         "src/core/support/string.h",
+        "src/core/support/string_win32.h",
         "src/core/support/thd_internal.h"
       ],
       "src": [
diff --git a/src/core/support/env_win32.c b/src/core/support/env_win32.c
index a31fa79..3159c20 100644
--- a/src/core/support/env_win32.c
+++ b/src/core/support/env_win32.c
@@ -39,6 +39,7 @@
 
 #include <stdlib.h>
 
+#include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
 char *gpr_getenv(const char *name) {
diff --git a/src/core/support/file_win32.c b/src/core/support/file_win32.c
index d415281..af7eebe 100644
--- a/src/core/support/file_win32.c
+++ b/src/core/support/file_win32.c
@@ -35,43 +35,48 @@
 
 #ifdef GPR_WIN32
 
-#include "src/core/support/file.h"
-
 #include <io.h>
 #include <stdio.h>
 #include <string.h>
+#include <tchar.h>
 
 #include <grpc/support/alloc.h>
 #include <grpc/support/log.h>
 
-FILE *gpr_tmpfile(const char *prefix, char **tmp_filename) {
+#include "src/core/support/file.h"
+#include "src/core/support/string_win32.h"
+
+FILE *gpr_tmpfile(const char *prefix, char **tmp_filename_out) {
   FILE *result = NULL;
-  char *template;
+  LPTSTR template_string = NULL;
+  TCHAR tmp_path[MAX_PATH];
+  TCHAR tmp_filename[MAX_PATH];
+  DWORD status;
+  UINT success;
 
-  if (tmp_filename != NULL) *tmp_filename = NULL;
+  if (tmp_filename_out != NULL) *tmp_filename_out = NULL;
 
-  gpr_asprintf(&template, "%s_XXXXXX", prefix);
-  GPR_ASSERT(template != NULL);
+  /* Convert our prefix to TCHAR. */
+  template_string = gpr_char_to_tchar(prefix);
+  GPR_ASSERT(template_string);
 
-  /* _mktemp_s can only create a maximum of 26 file names for any combination of
-     base and template values which is kind of sad... We may revisit this
-     function later to have something better... */
-  if (_mktemp_s(template, strlen(template) + 1) != 0) {
-    gpr_log(LOG_ERROR, "Could not create tmp file.");
-    goto end;
-  }
-  if (fopen_s(&result, template, "wb+") != 0) {
-    gpr_log(GPR_ERROR, "Could not open file %s", template);
-    result = NULL;
-    goto end;
-  }
+  /* Get the path to the best temporary folder available. */
+  status = GetTempPath(MAX_PATH, tmp_path);
+  if (status == 0 || status > MAX_PATH) goto end;
+
+  /* Generate a unique filename with our template + temporary path. */
+  success = GetTempFileName(tmp_path, template_string, 0, tmp_filename);
+  if (!success) goto end;
+
+  /* Open a file there. */
+  if (_tfopen_s(&result, tmp_filename, TEXT("wb+")) != 0) goto end;
 
 end:
-  if (result != NULL && tmp_filename != NULL) {
-    *tmp_filename = template;
-  } else {
-    gpr_free(template);
+  if (result && tmp_filename) {
+    *tmp_filename_out = gpr_tchar_to_char(tmp_filename);
   }
+
+  gpr_free(tmp_filename);
   return result;
 }
 
diff --git a/src/core/support/string_win32.c b/src/core/support/string_win32.c
index 1c4c854..02e1c74 100644
--- a/src/core/support/string_win32.c
+++ b/src/core/support/string_win32.c
@@ -37,6 +37,7 @@
 
 #ifdef GPR_WIN32
 
+#include <windows.h>
 #include <stdio.h>
 #include <stdarg.h>
 #include <string.h>
@@ -78,4 +79,32 @@
   return -1;
 }
 
+#if defined UNICODE || defined _UNICODE
+LPTSTR gpr_char_to_tchar(LPCSTR input) {
+  LPTSTR ret;
+  int needed = MultiByteToWideChar(CP_UTF8, 0, input, -1, NULL, 0);
+  if (needed == 0) return NULL;
+  ret = gpr_malloc(needed * sizeof(TCHAR));
+  MultiByteToWideChar(CP_UTF8, 0, input, -1, ret, needed);
+  return ret;
+}
+
+LPSTR gpr_tchar_to_char(LPCTSTR input) {
+  LPSTR ret;
+  int needed = WideCharToMultiByte(CP_UTF8, 0, input, -1, NULL, 0, NULL, NULL);
+  if (needed == 0) return NULL;
+  ret = gpr_malloc(needed);
+  WideCharToMultiByte(CP_UTF8, 0, input, -1, ret, needed, NULL, NULL);
+  return ret;
+}
+#else
+char *gpr_tchar_to_char(LPTSTR input) {
+  return gpr_strdup(input);
+}
+
+char *gpr_char_to_tchar(LPTSTR input) {
+  return gpr_strdup(input);
+}
+#endif
+
 #endif /* GPR_WIN32 */
diff --git a/src/core/support/string_win32.h b/src/core/support/string_win32.h
new file mode 100644
index 0000000..9102d98
--- /dev/null
+++ b/src/core/support/string_win32.h
@@ -0,0 +1,49 @@
+/*
+ *
+ * Copyright 2014, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef __GRPC_SUPPORT_STRING_WIN32_H__
+#define __GRPC_SUPPORT_STRING_WIN32_H__
+
+#include <grpc/support/port_platform.h>
+
+#ifdef GPR_WIN32
+
+#include <windows.h>
+
+/* These allocate new strings using gpr_malloc to convert from and to utf-8. */
+LPTSTR gpr_char_to_tchar(LPCSTR input);
+LPSTR gpr_tchar_to_char(LPCTSTR input);
+
+#endif  /* GPR_WIN32 */
+
+#endif /* __GRPC_SUPPORT_STRING_WIN32_H__ */
diff --git a/vsprojects/vs2013/gpr.vcxproj b/vsprojects/vs2013/gpr.vcxproj
index d1f7085..8276082 100644
--- a/vsprojects/vs2013/gpr.vcxproj
+++ b/vsprojects/vs2013/gpr.vcxproj
@@ -100,6 +100,7 @@
     <ClInclude Include="..\..\src\core\support\file.h" />
     <ClInclude Include="..\..\src\core\support\murmur_hash.h" />
     <ClInclude Include="..\..\src\core\support\string.h" />
+    <ClInclude Include="..\..\src\core\support\string_win32.h" />
     <ClInclude Include="..\..\src\core\support\thd_internal.h" />
   </ItemGroup>
   <ItemGroup>
diff --git a/vsprojects/vs2013/gpr.vcxproj.filters b/vsprojects/vs2013/gpr.vcxproj.filters
index 13add83..2329acc 100644
--- a/vsprojects/vs2013/gpr.vcxproj.filters
+++ b/vsprojects/vs2013/gpr.vcxproj.filters
@@ -176,6 +176,9 @@
     <ClInclude Include="..\..\src\core\support\string.h">
       <Filter>src\core\support</Filter>
     </ClInclude>
+    <ClInclude Include="..\..\src\core\support\string_win32.h">
+      <Filter>src\core\support</Filter>
+    </ClInclude>
     <ClInclude Include="..\..\src\core\support\thd_internal.h">
       <Filter>src\core\support</Filter>
     </ClInclude>