diff --git a/src/os_mac_conv.c b/src/os_mac_conv.c
new file mode 100644
index 0000000..3dfacfe
--- /dev/null
+++ b/src/os_mac_conv.c
@@ -0,0 +1,230 @@
+/* vi:set ts=8 sts=4 sw=4:
+ *
+ * VIM - Vi IMproved	by Bram Moolenaar
+ *
+ * Do ":help uganda"  in Vim to read copying and usage conditions.
+ * Do ":help credits" in Vim to see a list of people who contributed.
+ * See README.txt for an overview of the Vim source code.
+ */
+/*
+ * os_mac_conv.c: Code specifically for Mac string conversions.
+ *
+ * This code has been put in a separate file to avoid the conflicts that are
+ * caused by including both the X11 and Carbon header files.
+ */
+
+#define NO_X11_INCLUDES
+#include "vim.h"
+
+extern char_u *mac_string_convert __ARGS((char_u *ptr, int len, int *lenp, int fail_on_error, int from, int to, int *unconvlenp));
+extern int macroman2enc __ARGS((char_u *ptr, long *sizep, long real_size));
+extern int enc2macroman __ARGS((char_u *from, size_t fromlen, char_u *to, int *tolenp, int maxtolen, char_u *rest, int *restlenp));
+
+/*
+ * A Mac version of string_convert_ext() for special cases.
+ */
+    char_u *
+mac_string_convert(ptr, len, lenp, fail_on_error, from_enc, to_enc, unconvlenp)
+    char_u		*ptr;
+    int			len;
+    int			*lenp;
+    int			fail_on_error;
+    int			from_enc;
+    int			to_enc;
+    int			*unconvlenp;
+{
+    char_u		*retval, *d;
+    CFStringRef		cfstr;
+    int			buflen, in, out, l, i;
+    CFStringEncoding	from;
+    CFStringEncoding	to;
+
+    switch (from_enc)
+    {
+	case 'l':   from = kCFStringEncodingISOLatin1; break;
+	case 'm':   from = kCFStringEncodingMacRoman; break;
+	case 'u':   from = kCFStringEncodingUTF8; break;
+	default:    return NULL;
+    }
+    switch (to_enc)
+    {
+	case 'l':   to = kCFStringEncodingISOLatin1; break;
+	case 'm':   to = kCFStringEncodingMacRoman; break;
+	case 'u':   to = kCFStringEncodingUTF8; break;
+	default:    return NULL;
+    }
+
+    if (unconvlenp != NULL)
+	*unconvlenp = 0;
+    cfstr = CFStringCreateWithBytes(NULL, ptr, len, from, 0);
+
+    /* When conversion failed, try excluding bytes from the end, helps when
+     * there is an incomplete byte sequence.  Only do up to 6 bytes to avoid
+     * looping a long time when there really is something unconvertable. */
+    while (cfstr == NULL && unconvlenp != NULL && len > 1 && *unconvlenp < 6)
+    {
+	--len;
+	++*unconvlenp;
+	cfstr = CFStringCreateWithBytes(NULL, ptr, len, from, 0);
+    }
+    if (cfstr == NULL)
+	return NULL;
+    if (to == kCFStringEncodingUTF8)
+	buflen = len * 6 + 1;
+    else
+	buflen = len + 1;
+    retval = alloc(buflen);
+    if (retval == NULL)
+    {
+	CFRelease(cfstr);
+	return NULL;
+    }
+    if (!CFStringGetCString(cfstr, retval, buflen, to))
+    {
+	CFRelease(cfstr);
+	if (fail_on_error)
+	{
+	    vim_free(retval);
+	    return NULL;
+	}
+
+	/* conversion failed for the whole string, but maybe it will work
+	 * for each character */
+	for (d = retval, in = 0, out = 0; in < len && out < buflen - 1;)
+	{
+	    if (from == kCFStringEncodingUTF8)
+		l = utf_ptr2len_check(ptr + in);
+	    else
+		l = 1;
+	    cfstr = CFStringCreateWithBytes(NULL, ptr + in, l, from, 0);
+	    if (cfstr == NULL)
+	    {
+		*d++ = '?';
+		out++;
+	    }
+	    else
+	    {
+		if (!CFStringGetCString(cfstr, d, buflen - out, to))
+		{
+		    *d++ = '?';
+		    out++;
+		}
+		else
+		{
+		    i = strlen(d);
+		    d += i;
+		    out += i;
+		}
+		CFRelease(cfstr);
+	    }
+	    in += l;
+	}
+	*d = NUL;
+	if (lenp != NULL)
+	    *lenp = out;
+	return retval;
+    }
+    CFRelease(cfstr);
+    if (lenp != NULL)
+	*lenp = strlen(retval);
+    return retval;
+}
+
+/*
+ * Conversion from Apple MacRoman char encoding to UTF-8 or latin1, using
+ * standard Carbon framework.
+ * Input: "ptr[*sizep]".
+ * "real_size" is the size of the buffer that "ptr" points to.
+ * output is in-place, "sizep" is adjusted.
+ * Returns OK or FAIL.
+ */
+    int
+macroman2enc(ptr, sizep, real_size)
+    char_u	*ptr;
+    long	*sizep;
+    long	real_size;
+{
+    CFStringRef		cfstr;
+    CFRange		r;
+    CFIndex		len = *sizep;
+
+    /* MacRoman is an 8-bit encoding, no need to move bytes to
+     * conv_rest[]. */
+    cfstr = CFStringCreateWithBytes(NULL, ptr, len,
+						kCFStringEncodingMacRoman, 0);
+    /*
+     * If there is a conversion error, try using another
+     * conversion.
+     */
+    if (cfstr == NULL)
+	return FAIL;
+
+    r.location = 0;
+    r.length = CFStringGetLength(cfstr);
+    if (r.length != CFStringGetBytes(cfstr, r,
+	    (enc_utf8) ? kCFStringEncodingUTF8 : kCFStringEncodingISOLatin1,
+	    0, /* no lossy conversion */
+	    0, /* not external representation */
+	    ptr + *sizep, real_size - *sizep, &len))
+    {
+	CFRelease(cfstr);
+	return FAIL;
+    }
+    CFRelease(cfstr);
+    mch_memmove(ptr, ptr + *sizep, len);
+    *sizep = len;
+
+    return OK;
+}
+
+/*
+ * Conversion from UTF-8 or latin1 to MacRoman.
+ * Input: "from[fromlen]"
+ * Output: "to[maxtolen]" length in "*tolenp"
+ * Unconverted rest in rest[*restlenp].
+ * Returns OK or FAIL.
+ */
+    int
+enc2macroman(from, fromlen, to, tolenp, maxtolen, rest, restlenp)
+    char_u	*from;
+    size_t	fromlen;
+    char_u	*to;
+    int		*tolenp;
+    int		maxtolen;
+    char_u	*rest;
+    int		*restlenp;
+{
+    CFStringRef	cfstr;
+    CFRange	r;
+    CFIndex	l;
+
+    *restlenp = 0;
+    cfstr = CFStringCreateWithBytes(NULL, from, fromlen,
+	    (enc_utf8) ? kCFStringEncodingUTF8 : kCFStringEncodingISOLatin1,
+	    0);
+    while (cfstr == NULL && *restlenp < 3 && fromlen > 1)
+    {
+	rest[*restlenp++] = from[--fromlen];
+	cfstr = CFStringCreateWithBytes(NULL, from, fromlen,
+		(enc_utf8) ? kCFStringEncodingUTF8 : kCFStringEncodingISOLatin1,
+		0);
+    }
+    if (cfstr == NULL)
+	return FAIL;
+
+    r.location = 0;
+    r.length = CFStringGetLength(cfstr);
+    if (r.length != CFStringGetBytes(cfstr, r,
+		kCFStringEncodingMacRoman,
+		0, /* no lossy conversion */
+		0, /* not external representation (since vim
+		    * handles this internally */
+		to, maxtolen, &l))
+    {
+	CFRelease(cfstr);
+	return FAIL;
+    }
+    CFRelease(cfstr);
+    *tolenp = l;
+    return OK;
+}