diff --git a/npa/src/npa-tool.c b/npa/src/npa-tool.c
index bfa6535..34dc521 100644
--- a/npa/src/npa-tool.c
+++ b/npa/src/npa-tool.c
@@ -287,6 +287,8 @@ main (int argc, char **argv)
     size_t privkey_len = 0;
     unsigned char auxiliary_data[0xff];
     size_t auxiliary_data_len = 0;
+    unsigned char community_id[0xf];
+    size_t community_id_len = 0;
 
     sc_context_t *ctx = NULL;
     sc_card_t *card = NULL;
@@ -605,10 +607,15 @@ main (int argc, char **argv)
                         goto err;
                 }
                 if (cmdline.verify_community_given) {
+                    community_id_len = sizeof community_id;
+                    if (sc_hex_to_bin(cmdline.verify_community_arg, community_id,
+                                &community_id_len) < 0) {
+                        fprintf(stderr, "Could not parse community ID.\n");
+                        exit(2);
+                    }
                     r = add_to_ASN1_AUXILIARY_DATA(&templates,
                             NID_id_CommunityID,
-                            (unsigned char *) cmdline.verify_community_arg,
-                            strlen(cmdline.verify_community_arg));
+                            community_id, community_id_len);
                     if (r < 0)
                         goto err;
                 }
diff --git a/npa/src/npa-tool.ggo.in b/npa/src/npa-tool.ggo.in
index d464919..2df8c08 100644
--- a/npa/src/npa-tool.ggo.in
+++ b/npa/src/npa-tool.ggo.in
@@ -69,7 +69,7 @@ option "chat"           -
     typestr="HEX_STRING"
     optional
 option "auxiliary-data" A
-    "Terminal's auxiliary data (default is determined by age verification and community id verification)."
+    "Terminal's auxiliary data (default is determined by verification of validity, age and community ID)."
     string
     typestr="HEX_STRING"
     optional
@@ -189,7 +189,7 @@ option "write-dg21"      -
 
 section "Verification of validity, age and community ID"
 option "verify-validity"    -
-    "Verify the chip's validity with a reference date"
+    "Verify chip's validity with a reference date"
     string
     typestr="YYYYMMDD"
     optional
@@ -201,6 +201,7 @@ option "older-than"     -
 option "verify-community"   -
     "Verify community ID with a reference ID"
     string
+    typestr="HEX_STRING"
     optional
 
 section "Special options, not always useful"