idx is unsigned, no need to check for < 0

--HG--
branch : HEAD
diff --git a/lib/zip_replace.c b/lib/zip_replace.c
index 03d66d5..c444e78 100644
--- a/lib/zip_replace.c
+++ b/lib/zip_replace.c
@@ -40,7 +40,7 @@
 ZIP_EXTERN int
 zip_replace(struct zip *za, zip_uint64_t idx, struct zip_source *source)
 {
-    if (idx < 0 || idx >= za->nentry || source == NULL) {
+    if (idx >= za->nentry || source == NULL) {
 	_zip_error_set(&za->error, ZIP_ER_INVAL, 0);
 	return -1;
     }