diff --git a/ext/unicode/unicode_filter.c b/ext/unicode/unicode_filter.c
index 5c645d05dae..3f28c9b09a7 100644
--- a/ext/unicode/unicode_filter.c
+++ b/ext/unicode/unicode_filter.c
@@ -144,7 +144,7 @@ static php_stream_filter_status_t php_unicode_from_string_filter(
 
 			destp = destbuf = (UChar *)pemalloc(destlen, data->is_persistent);
 
-			ucnv_toUnicode(data->conv, &destp, destbuf + destlen, (const char**)&src, src + remaining, NULL, FALSE, &errCode);
+			ucnv_toUnicode(data->conv, &destp, (UChar*)((char*)destbuf + destlen), (const char**)&src, src + remaining, NULL, FALSE, &errCode);
 
 			new_bucket = php_stream_bucket_new_unicode(stream, destbuf, destp - destbuf, 1, data->is_persistent TSRMLS_CC);
 			php_stream_bucket_append(buckets_out, new_bucket TSRMLS_CC);