diff --git a/src/ecopcr.c b/src/ecopcr.c
index 66c4bea..3c0f275 100644
--- a/src/ecopcr.c
+++ b/src/ecopcr.c
@@ -42,6 +42,7 @@ static void PrintHelp()
         PP      "-r    : [R]estricts the search to the given taxonomic id.\n");
         PP      "        Taxonomy id are available using the ecofind program.\n");
         PP      "        see its help typing ecofind -h for more information.\n");
+        PP      "-c    : Consider that the database sequences are [c]ircular");
         PP      "\n");
         PP      "------------------------------------------\n");
         PP      "first argument : oligonucleotide for direct strand\n\n");