diff --git a/dlls/api-ms-win-crt-multibyte-l1-1-0/api-ms-win-crt-multibyte-l1-1-0.spec b/dlls/api-ms-win-crt-multibyte-l1-1-0/api-ms-win-crt-multibyte-l1-1-0.spec
index 1c987d0fc74..31ccd0fd11e 100644
--- a/dlls/api-ms-win-crt-multibyte-l1-1-0/api-ms-win-crt-multibyte-l1-1-0.spec
+++ b/dlls/api-ms-win-crt-multibyte-l1-1-0/api-ms-win-crt-multibyte-l1-1-0.spec
@@ -23,7 +23,7 @@
 @ cdecl _ismbbpunct(long) ucrtbase._ismbbpunct
 @ stub _ismbbpunct_l
 @ cdecl _ismbbtrail(long) ucrtbase._ismbbtrail
-@ stub _ismbbtrail_l
+@ cdecl _ismbbtrail_l(long ptr) ucrtbase._ismbbtrail_l
 @ cdecl _ismbcalnum(long) ucrtbase._ismbcalnum
 @ stub _ismbcalnum_l
 @ cdecl _ismbcalpha(long) ucrtbase._ismbcalpha
diff --git a/dlls/msvcr100/msvcr100.spec b/dlls/msvcr100/msvcr100.spec
index c4574c67057..5e30c7772a1 100644
--- a/dlls/msvcr100/msvcr100.spec
+++ b/dlls/msvcr100/msvcr100.spec
@@ -973,7 +973,7 @@
 @ stub _ismbbpunct(long)
 @ stub _ismbbpunct_l
 @ cdecl _ismbbtrail(long)
-@ stub _ismbbtrail_l
+@ cdecl _ismbbtrail_l(long ptr)
 @ cdecl _ismbcalnum(long)
 @ stub _ismbcalnum_l
 @ cdecl _ismbcalpha(long)
diff --git a/dlls/msvcr110/msvcr110.spec b/dlls/msvcr110/msvcr110.spec
index 59ed70310ca..8f35f48bd12 100644
--- a/dlls/msvcr110/msvcr110.spec
+++ b/dlls/msvcr110/msvcr110.spec
@@ -1319,7 +1319,7 @@
 @ stub _ismbbpunct(long)
 @ stub _ismbbpunct_l
 @ cdecl _ismbbtrail(long)
-@ stub _ismbbtrail_l
+@ cdecl _ismbbtrail_l(long ptr)
 @ cdecl _ismbcalnum(long)
 @ stub _ismbcalnum_l
 @ cdecl _ismbcalpha(long)
diff --git a/dlls/msvcr120/msvcr120.spec b/dlls/msvcr120/msvcr120.spec
index 4e25c6898df..49b33272d5c 100644
--- a/dlls/msvcr120/msvcr120.spec
+++ b/dlls/msvcr120/msvcr120.spec
@@ -1322,7 +1322,7 @@
 @ stub _ismbbpunct(long)
 @ stub _ismbbpunct_l
 @ cdecl _ismbbtrail(long)
-@ stub _ismbbtrail_l
+@ cdecl _ismbbtrail_l(long ptr)
 @ cdecl _ismbcalnum(long)
 @ stub _ismbcalnum_l
 @ cdecl _ismbcalpha(long)
diff --git a/dlls/msvcr120_app/msvcr120_app.spec b/dlls/msvcr120_app/msvcr120_app.spec
index c1f6e0bcf08..e3323dd83ad 100644
--- a/dlls/msvcr120_app/msvcr120_app.spec
+++ b/dlls/msvcr120_app/msvcr120_app.spec
@@ -1225,7 +1225,7 @@
 @ cdecl _ismbbpunct(long) msvcr120._ismbbpunct
 @ stub _ismbbpunct_l
 @ cdecl _ismbbtrail(long) msvcr120._ismbbtrail
-@ stub _ismbbtrail_l
+@ cdecl _ismbbtrail_l(long ptr) msvcr120._ismbbtrail_l
 @ cdecl _isnan(double) msvcr120._isnan
 @ cdecl -arch=x86_64 _isnanf(float) msvcr120._isnanf
 @ cdecl _isprint_l(long ptr) msvcr120._isprint_l
diff --git a/dlls/msvcr80/msvcr80.spec b/dlls/msvcr80/msvcr80.spec
index c9863d953c6..c1b3d8bd5cd 100644
--- a/dlls/msvcr80/msvcr80.spec
+++ b/dlls/msvcr80/msvcr80.spec
@@ -645,7 +645,7 @@
 @ stub _ismbbpunct(long)
 @ stub _ismbbpunct_l
 @ cdecl _ismbbtrail(long)
-@ stub _ismbbtrail_l
+@ cdecl _ismbbtrail_l(long ptr)
 @ cdecl _ismbcalnum(long)
 @ stub _ismbcalnum_l
 @ cdecl _ismbcalpha(long)
diff --git a/dlls/msvcr90/msvcr90.spec b/dlls/msvcr90/msvcr90.spec
index b6861223ed9..3da8fdf991c 100644
--- a/dlls/msvcr90/msvcr90.spec
+++ b/dlls/msvcr90/msvcr90.spec
@@ -623,7 +623,7 @@
 @ stub _ismbbpunct(long)
 @ stub _ismbbpunct_l
 @ cdecl _ismbbtrail(long)
-@ stub _ismbbtrail_l
+@ cdecl _ismbbtrail_l(long ptr)
 @ cdecl _ismbcalnum(long)
 @ stub _ismbcalnum_l
 @ cdecl _ismbcalpha(long)
diff --git a/dlls/msvcrt/mbcs.c b/dlls/msvcrt/mbcs.c
index d00c31af4cf..d470f100e3f 100644
--- a/dlls/msvcrt/mbcs.c
+++ b/dlls/msvcrt/mbcs.c
@@ -1551,13 +1551,27 @@ int CDECL _ismbblead(unsigned int c)
     return _ismbblead_l(c, NULL);
 }
 
+/*********************************************************************
+ *              _ismbbtrail_l(MSVCRT.@)
+ */
+int CDECL _ismbbtrail_l(unsigned int c, MSVCRT__locale_t locale)
+{
+    MSVCRT_pthreadmbcinfo mbcinfo;
+
+    if(!locale)
+        mbcinfo = get_mbcinfo();
+    else
+        mbcinfo = locale->mbcinfo;
+
+    return (mbcinfo->mbctype[(c&0xff) + 1] & _M2) != 0;
+}
 
 /*********************************************************************
  *		_ismbbtrail(MSVCRT.@)
  */
 int CDECL _ismbbtrail(unsigned int c)
 {
-  return (get_mbcinfo()->mbctype[(c&0xff) + 1] & _M2) != 0;
+    return _ismbbtrail_l(c, NULL);
 }
 
 /*********************************************************************
diff --git a/dlls/msvcrt/msvcrt.spec b/dlls/msvcrt/msvcrt.spec
index 2a74d5186c7..0154998f059 100644
--- a/dlls/msvcrt/msvcrt.spec
+++ b/dlls/msvcrt/msvcrt.spec
@@ -594,7 +594,7 @@
 @ stub _ismbbpunct(long)
 # stub _ismbbpunct_l(long ptr)
 @ cdecl _ismbbtrail(long)
-# stub _ismbbtrail_l(long ptr)
+@ cdecl _ismbbtrail_l(long ptr)
 @ cdecl _ismbcalnum(long)
 # stub _ismbcalnum_l(long ptr)
 @ cdecl _ismbcalpha(long)
diff --git a/dlls/ucrtbase/ucrtbase.spec b/dlls/ucrtbase/ucrtbase.spec
index 2d1d8da3562..021d9b24e4f 100644
--- a/dlls/ucrtbase/ucrtbase.spec
+++ b/dlls/ucrtbase/ucrtbase.spec
@@ -461,7 +461,7 @@
 @ stub _ismbbpunct(long)
 @ stub _ismbbpunct_l
 @ cdecl _ismbbtrail(long)
-@ stub _ismbbtrail_l
+@ cdecl _ismbbtrail_l(long ptr)
 @ cdecl _ismbcalnum(long)
 @ stub _ismbcalnum_l
 @ cdecl _ismbcalpha(long)