diff --git a/src/mbyte.c b/src/mbyte.c
index 80f6691..fe12c57 100644
--- a/src/mbyte.c
+++ b/src/mbyte.c
@@ -6256,8 +6256,23 @@
 	    if (vcp->vc_cpfrom == 0)
 		tmp_len = utf8_to_utf16(ptr, len, NULL, NULL);
 	    else
-		tmp_len = MultiByteToWideChar(vcp->vc_cpfrom, 0,
-							      ptr, len, 0, 0);
+	    {
+		tmp_len = MultiByteToWideChar(vcp->vc_cpfrom,
+					unconvlenp ? MB_ERR_INVALID_CHARS : 0,
+					ptr, len, 0, 0);
+		if (tmp_len == 0
+			&& GetLastError() == ERROR_NO_UNICODE_TRANSLATION)
+		{
+		    if (lenp != NULL)
+			*lenp = 0;
+		    if (unconvlenp != NULL)
+			*unconvlenp = len;
+		    retval = alloc(1);
+		    if (retval)
+			retval[0] = NUL;
+		    return retval;
+		}
+	    }
 	    tmp = (short_u *)alloc(sizeof(short_u) * tmp_len);
 	    if (tmp == NULL)
 		break;