diff --git a/README.md b/README.md
index 31774abfb6c8ec918aa7bec8ddcdec014053a2c0..8766e9fbde6ea813832892fce23c750463ef07ab 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ The suggestion is to run it with one mpi task per socket.
  - -t --in-type        *(required)* datatype of the input file, allowed choices `f32`, `f64`
  - -d --in-dims        *(required)* number of dimensions of the data file, dadp expects something of the form N x d where N is inferred from the lenght of the data file
  - -o --out-data       *(optional)* output path for the data, the datafile is shuffled between mpi tasks and datapoints are ordered default is `out_data`
- - -a --out-assignment *(optional)* output path for the cluster assignment output ranges [0 ... Nc - 1] for core points halo points have indices [-Nc ... -1] conversion of idx for an halo point is `cluster_idx = -halo_idx - 1`
+ - -a --out-assignment *(optional)* output path for the cluster assignment output ranges [0 ... Nc - 1] for core points halo points have indices [-Nc ... -1] conversion of idx for an halo point is `cluster_idx = -halo_idx - 1`, default is `out_assignment`
 
 # TODO
 
diff --git a/src/main/main.c b/src/main/main.c
index ac205230c4ad2b4e51390e9584bbbbf00e09749b..2c09e47f2652b25ea2b6e184a091c5eb4ed8addb 100644
--- a/src/main/main.c
+++ b/src/main/main.c
@@ -59,7 +59,7 @@ const char* help = "Distributed Advanced Density Peak\n"\
                    "                                   mpi tasks and datapoints are ordered default is `out_data` \n"\
                    "    -a --out-assignment (optional) output path for the cluster assignment output ranges [0 ... Nc - 1]\n"\
                    "                                   for core points halo points have indices [-Nc ... -1] conversion\n"\
-                   "                                   of idx for an halo point is cluster_idx = -halo_idx - 1\n";
+                   "                                   of idx for an halo point is cluster_idx = -halo_idx - 1, default is `out_assignment`\n";
 
 void parse_args(global_context_t* ctx, int argc, char** argv)
 {