diff --git a/src/http_htx.c b/src/http_htx.c
index b27b083..9570b1e 100644
--- a/src/http_htx.c
+++ b/src/http_htx.c
@@ -201,7 +201,7 @@
 					goto next_blk;
 				break;
 			case HTTP_FIND_FL_MATCH_SUB:
-				if (strnistr(n.ptr, n.len, name.ptr, n.len) != NULL)
+				if (!strnistr(n.ptr, n.len, name.ptr, name.len))
 					goto next_blk;
 				break;
 			default: