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 1034c209703..3ab70829ca9 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
@@ -53,7 +53,7 @@
 @ cdecl _ismbcpunct(long) ucrtbase._ismbcpunct
 @ stub _ismbcpunct_l
 @ cdecl _ismbcspace(long) ucrtbase._ismbcspace
-@ stub _ismbcspace_l
+@ cdecl _ismbcspace_l(long ptr) ucrtbase._ismbcspace_l
 @ cdecl _ismbcsymbol(long) ucrtbase._ismbcsymbol
 @ stub _ismbcsymbol_l
 @ cdecl _ismbcupper(long) ucrtbase._ismbcupper
diff --git a/dlls/api-ms-win-crt-private-l1-1-0/api-ms-win-crt-private-l1-1-0.spec b/dlls/api-ms-win-crt-private-l1-1-0/api-ms-win-crt-private-l1-1-0.spec
index 61992d3a463..22ac50e14a5 100644
--- a/dlls/api-ms-win-crt-private-l1-1-0/api-ms-win-crt-private-l1-1-0.spec
+++ b/dlls/api-ms-win-crt-private-l1-1-0/api-ms-win-crt-private-l1-1-0.spec
@@ -426,7 +426,7 @@
 @ cdecl _o__ismbcpunct(long) ucrtbase._o__ismbcpunct
 @ stub _o__ismbcpunct_l
 @ cdecl _o__ismbcspace(long) ucrtbase._o__ismbcspace
-@ stub _o__ismbcspace_l
+@ cdecl _o__ismbcspace_l(long ptr) ucrtbase._o__ismbcspace_l
 @ cdecl _o__ismbcsymbol(long) ucrtbase._o__ismbcsymbol
 @ stub _o__ismbcsymbol_l
 @ cdecl _o__ismbcupper(long) ucrtbase._o__ismbcupper
diff --git a/dlls/msvcr100/msvcr100.spec b/dlls/msvcr100/msvcr100.spec
index 43d92304aaa..30aaa302ef2 100644
--- a/dlls/msvcr100/msvcr100.spec
+++ b/dlls/msvcr100/msvcr100.spec
@@ -1001,7 +1001,7 @@
 @ cdecl _ismbcpunct(long)
 @ stub _ismbcpunct_l
 @ cdecl _ismbcspace(long)
-@ stub _ismbcspace_l
+@ cdecl _ismbcspace_l(long ptr)
 @ cdecl _ismbcsymbol(long)
 @ stub _ismbcsymbol_l
 @ cdecl _ismbcupper(long)
diff --git a/dlls/msvcr110/msvcr110.spec b/dlls/msvcr110/msvcr110.spec
index 0acb77474e0..6bf022ac748 100644
--- a/dlls/msvcr110/msvcr110.spec
+++ b/dlls/msvcr110/msvcr110.spec
@@ -1347,7 +1347,7 @@
 @ cdecl _ismbcpunct(long)
 @ stub _ismbcpunct_l
 @ cdecl _ismbcspace(long)
-@ stub _ismbcspace_l
+@ cdecl _ismbcspace_l(long ptr)
 @ cdecl _ismbcsymbol(long)
 @ stub _ismbcsymbol_l
 @ cdecl _ismbcupper(long)
diff --git a/dlls/msvcr120/msvcr120.spec b/dlls/msvcr120/msvcr120.spec
index 26ebdd2445b..48d58977a73 100644
--- a/dlls/msvcr120/msvcr120.spec
+++ b/dlls/msvcr120/msvcr120.spec
@@ -1352,7 +1352,7 @@
 @ cdecl _ismbcpunct(long)
 @ stub _ismbcpunct_l
 @ cdecl _ismbcspace(long)
-@ stub _ismbcspace_l
+@ cdecl _ismbcspace_l(long ptr)
 @ cdecl _ismbcsymbol(long)
 @ stub _ismbcsymbol_l
 @ cdecl _ismbcupper(long)
diff --git a/dlls/msvcr80/msvcr80.spec b/dlls/msvcr80/msvcr80.spec
index 93b5be804d7..ddf81b48589 100644
--- a/dlls/msvcr80/msvcr80.spec
+++ b/dlls/msvcr80/msvcr80.spec
@@ -673,7 +673,7 @@
 @ cdecl _ismbcpunct(long)
 @ stub _ismbcpunct_l
 @ cdecl _ismbcspace(long)
-@ stub _ismbcspace_l
+@ cdecl _ismbcspace_l(long ptr)
 @ cdecl _ismbcsymbol(long)
 @ stub _ismbcsymbol_l
 @ cdecl _ismbcupper(long)
diff --git a/dlls/msvcr90/msvcr90.spec b/dlls/msvcr90/msvcr90.spec
index 5dccd7cf306..9a86afb37ce 100644
--- a/dlls/msvcr90/msvcr90.spec
+++ b/dlls/msvcr90/msvcr90.spec
@@ -651,7 +651,7 @@
 @ cdecl _ismbcpunct(long)
 @ stub _ismbcpunct_l
 @ cdecl _ismbcspace(long)
-@ stub _ismbcspace_l
+@ cdecl _ismbcspace_l(long ptr)
 @ cdecl _ismbcsymbol(long)
 @ stub _ismbcsymbol_l
 @ cdecl _ismbcupper(long)
diff --git a/dlls/msvcrt/mbcs.c b/dlls/msvcrt/mbcs.c
index 59dcbcc4fee..e93aafc44ae 100644
--- a/dlls/msvcrt/mbcs.c
+++ b/dlls/msvcrt/mbcs.c
@@ -1538,13 +1538,20 @@ int CDECL _ismbcalnum(unsigned int ch)
     return _ismbcalnum_l( ch, NULL );
 }
 
+/*********************************************************************
+ *              _ismbcspace_l (MSVCRT.@)
+ */
+int CDECL _ismbcspace_l(unsigned int ch, MSVCRT__locale_t locale)
+{
+    return MSVCRT__iswspace_l( msvcrt_mbc_to_wc_l(ch, locale), locale );
+}
+
 /*********************************************************************
  *              _ismbcspace (MSVCRT.@)
  */
 int CDECL _ismbcspace(unsigned int ch)
 {
-    MSVCRT_wchar_t wch = msvcrt_mbc_to_wc( ch );
-    return (get_char_typeW( wch ) & C1_SPACE);
+    return _ismbcspace_l( ch, NULL );
 }
 
 /*********************************************************************
diff --git a/dlls/msvcrt/msvcrt.spec b/dlls/msvcrt/msvcrt.spec
index 5f68220d4b4..12c4a718e80 100644
--- a/dlls/msvcrt/msvcrt.spec
+++ b/dlls/msvcrt/msvcrt.spec
@@ -619,7 +619,7 @@
 @ cdecl _ismbcpunct(long)
 # stub _ismbcpunct_l(long ptr)
 @ cdecl _ismbcspace(long)
-# stub _ismbcspace_l(long ptr)
+@ cdecl _ismbcspace_l(long ptr)
 @ cdecl _ismbcsymbol(long)
 # stub _ismbcsymbol_l(long ptr)
 @ cdecl _ismbcupper(long)
diff --git a/dlls/ucrtbase/ucrtbase.spec b/dlls/ucrtbase/ucrtbase.spec
index 2492fec1e60..c93d0cee049 100644
--- a/dlls/ucrtbase/ucrtbase.spec
+++ b/dlls/ucrtbase/ucrtbase.spec
@@ -491,7 +491,7 @@
 @ cdecl _ismbcpunct(long)
 @ stub _ismbcpunct_l
 @ cdecl _ismbcspace(long)
-@ stub _ismbcspace_l
+@ cdecl _ismbcspace_l(long ptr)
 @ cdecl _ismbcsymbol(long)
 @ stub _ismbcsymbol_l
 @ cdecl _ismbcupper(long)
@@ -1090,7 +1090,7 @@
 @ cdecl _o__ismbcpunct(long) _ismbcpunct
 @ stub _o__ismbcpunct_l
 @ cdecl _o__ismbcspace(long) _ismbcspace
-@ stub _o__ismbcspace_l
+@ cdecl _o__ismbcspace_l(long ptr) _ismbcspace_l
 @ cdecl _o__ismbcsymbol(long) _ismbcsymbol
 @ stub _o__ismbcsymbol_l
 @ cdecl _o__ismbcupper(long) _ismbcupper