diff --git a/src/option.c b/src/option.c
index b26c606..185a928 100644
--- a/src/option.c
+++ b/src/option.c
@@ -8243,6 +8243,55 @@
 	    if (p != NULL)
 	    {
 		vim_setenv(envname, p);
+		if (vim_getenv((char_u *)"MYVIMDIR", &dofree) == NULL)
+		{
+		    size_t  usedlen = 0;
+		    int     len = 0;
+		    char_u  *fbuf = NULL;
+
+		    if (STRNCMP(gettail(fname), ".vimrc", 6) == 0)
+		    {
+			len = STRLEN(p) - 2;
+			p[len] = '/';
+		    }
+		    else if (STRNCMP(gettail(fname), ".gvimrc", 7) == 0)
+		    {
+			len = STRLEN(p);
+			char_u  *buf = alloc(len);
+			if (buf != NULL)
+			{
+			    mch_memmove(buf, fname, len - 7);
+			    mch_memmove(buf + len - 7, (char_u *)".vim/", 5);
+			    len -= 2;  // decrement len, so that we can set len+1 = NUL below
+			    vim_free(p);
+			    p = buf;
+			}
+		    }
+#ifdef MSWIN
+		    else if (STRNCMP(gettail(fname), "_vimrc", 6) == 0)
+		    {
+			len = STRLEN(p) + 4; // remove _vimrc, add vimfiles/
+			char_u  *buf = alloc(len);
+			if (buf != NULL)
+			{
+			    mch_memmove(buf, fname, len - 10);
+			    mch_memmove(buf + len - 10, (char_u *)"vimfiles\\", 9);
+			    len -= 2;  // decrement len, so that we can set len+1 = NUL below
+			    vim_free(p);
+			    p = buf;
+			}
+		    }
+#endif
+		    else
+			(void)modify_fname((char_u *)":h", FALSE, &usedlen, &p, &fbuf, &len);
+
+		    if (p != NULL)
+		    {
+			// keep the directory separator
+			p[len + 1] = NUL;
+			vim_setenv((char_u *)"MYVIMDIR", p);
+		    }
+		}
 		vim_free(p);
 	    }
 	}