diff --git a/net/colo-compare.c b/net/colo-compare.c
index 1225f40e41..b966e7e514 100644
--- a/net/colo-compare.c
+++ b/net/colo-compare.c
@@ -807,7 +807,7 @@ static int compare_chr_send(CompareState *s,
     }
 
     if (!size) {
-        return 0;
+        return -1;
     }
 
     entry = g_slice_new(SendEntry);