diff --git a/src/misc1.c b/src/misc1.c
index cc5d5e6..f95c3fe 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -4453,9 +4453,6 @@
     {
 	sprintf((char *)envbuf, "%s=%s", name, val);
 	putenv((char *)envbuf);
-# ifdef libintl_putenv
-	libintl_putenv((char *)envbuf);
-# endif
     }
 #endif
 #ifdef FEAT_GETTEXT
diff --git a/src/os_win32.c b/src/os_win32.c
index 9b86478..030b4b0 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -515,6 +515,7 @@
 static char *null_libintl_bindtextdomain(const char *, const char *);
 static char *null_libintl_bind_textdomain_codeset(const char *, const char *);
 static int null_libintl_putenv(const char *);
+static int null_libintl_wputenv(const wchar_t *);
 
 static HINSTANCE hLibintlDLL = NULL;
 char *(*dyn_libintl_gettext)(const char *) = null_libintl_gettext;
@@ -526,6 +527,7 @@
 char *(*dyn_libintl_bind_textdomain_codeset)(const char *, const char *)
 				       = null_libintl_bind_textdomain_codeset;
 int (*dyn_libintl_putenv)(const char *) = null_libintl_putenv;
+int (*dyn_libintl_wputenv)(const wchar_t *) = null_libintl_wputenv;
 
     int
 dyn_libintl_init(void)
@@ -591,9 +593,14 @@
     /* _putenv() function for the libintl.dll is optional. */
     hmsvcrt = find_imported_module_by_funcname(hLibintlDLL, "getenv");
     if (hmsvcrt != NULL)
+    {
 	dyn_libintl_putenv = (void *)GetProcAddress(hmsvcrt, "_putenv");
-    if (dyn_libintl_putenv == NULL || dyn_libintl_putenv == putenv)
+	dyn_libintl_wputenv = (void *)GetProcAddress(hmsvcrt, "_wputenv");
+    }
+    if (dyn_libintl_putenv == NULL || dyn_libintl_putenv == _putenv)
 	dyn_libintl_putenv = null_libintl_putenv;
+    if (dyn_libintl_wputenv == NULL || dyn_libintl_wputenv == _wputenv)
+	dyn_libintl_wputenv = null_libintl_wputenv;
 
     return 1;
 }
@@ -610,6 +617,7 @@
     dyn_libintl_bindtextdomain	= null_libintl_bindtextdomain;
     dyn_libintl_bind_textdomain_codeset = null_libintl_bind_textdomain_codeset;
     dyn_libintl_putenv		= null_libintl_putenv;
+    dyn_libintl_wputenv		= null_libintl_wputenv;
 }
 
 /*ARGSUSED*/
@@ -658,6 +666,13 @@
     return 0;
 }
 
+/*ARGSUSED*/
+    int
+null_libintl_wputenv(const wchar_t *envstring)
+{
+    return 0;
+}
+
 #endif /* DYNAMIC_GETTEXT */
 
 /* This symbol is not defined in older versions of the SDK or Visual C++ */
@@ -6985,3 +7000,43 @@
     set_alist_count();
 }
 #endif
+
+    int
+mch_setenv(char *var, char *value, int x)
+{
+    char_u	*envbuf;
+
+    envbuf = alloc((unsigned)(STRLEN(var) + STRLEN(value) + 2));
+    if (envbuf == NULL)
+	return -1;
+
+    sprintf((char *)envbuf, "%s=%s", var, value);
+
+#ifdef FEAT_MBYTE
+    if (enc_codepage >= 0 && (int)GetACP() != enc_codepage)
+    {
+	WCHAR	    *p = enc_to_utf16(envbuf, NULL);
+
+	vim_free(envbuf);
+	if (p == NULL)
+	    return -1;
+	_wputenv(p);
+# ifdef libintl_wputenv
+	libintl_wputenv(p);
+# endif
+	/* Unlike Un*x systems, we can free the string for _wputenv(). */
+	vim_free(p);
+    }
+    else
+#endif
+    {
+	_putenv((char *)envbuf);
+# ifdef libintl_putenv
+	libintl_putenv((char *)envbuf);
+# endif
+	/* Unlike Un*x systems, we can free the string for _putenv(). */
+	vim_free(envbuf);
+    }
+
+    return 0;
+}
diff --git a/src/os_win32.h b/src/os_win32.h
index f620d74..5017f53 100644
--- a/src/os_win32.h
+++ b/src/os_win32.h
@@ -202,7 +202,9 @@
 #define ASSERT_NULL_OR_POINTER(p, type) \
     ASSERT(((p) == NULL)  ||  IsValidAddress((p), sizeof(type), FALSE))
 
-#define mch_setenv(name, val, x) setenv(name, val, x)
+#ifndef HAVE_SETENV
+# define HAVE_SETENV
+#endif
 #define mch_getenv(x) (char_u *)getenv((char *)(x))
 #ifdef __BORLANDC__
 # define vim_mkdir(x, y) mkdir(x)
diff --git a/src/proto/os_win32.pro b/src/proto/os_win32.pro
index a64c863..ca67146 100644
--- a/src/proto/os_win32.pro
+++ b/src/proto/os_win32.pro
@@ -65,4 +65,5 @@
 void used_file_arg(char *name, int literal, int full_path, int diff_mode);
 void set_alist_count(void);
 void fix_arg_enc(void);
+int mch_setenv(char *var, char *value, int x);
 /* vim: set ft=c : */
diff --git a/src/version.c b/src/version.c
index 82ee6d4..08e32cf 100644
--- a/src/version.c
+++ b/src/version.c
@@ -765,6 +765,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    280,
+/**/
     279,
 /**/
     278,
diff --git a/src/vim.h b/src/vim.h
index abee386..f3e87fe 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -594,6 +594,7 @@
 #  endif
 #  define textdomain(domain) (*dyn_libintl_textdomain)(domain)
 #  define libintl_putenv(envstring) (*dyn_libintl_putenv)(envstring)
+#  define libintl_wputenv(envstring) (*dyn_libintl_wputenv)(envstring)
 # else
 #  include <libintl.h>
 #  define _(x) gettext((char *)(x))