diff --git a/tool/cmd_data.cpp b/tool/cmd_data.cpp
index f567ef83..64222279 100644
--- a/tool/cmd_data.cpp
+++ b/tool/cmd_data.cpp
@@ -17,9 +17,9 @@ const char *help_data =
     "Output binary domain data.\n"
     "\n"
     "Command-specific options:\n"
-    "  --domain -d <index> Positive numerical domain index. If this option\n"
-    "                      is not specified, data of all domains are\n"
-    "                      concatenated.\n";
+    "  --domain -d <index> Positive numerical domain index, or 'all' for\n"
+    "                      all domains (default). In this case, data of all\n"
+    "                      domains are concatenated.\n";
 
 /****************************************************************************/
 
diff --git a/tool/cmd_domain.cpp b/tool/cmd_domain.cpp
index aa559ea0..d144ffca 100644
--- a/tool/cmd_domain.cpp
+++ b/tool/cmd_domain.cpp
@@ -39,10 +39,9 @@ const char *help_domains =
     "The process data are displayed as raw hexadecimal bytes.\n"
     "\n"
     "Command-specific options:\n"
-    "  --domain   -d <index> Positive numerical domain index. If this\n"
-    "                        option is not specified, all domains are\n"
-    "                        displayed.\n"
-    "  --verbose  -v         Show FMMUs and process data.\n";
+    "  --domain   -d <index> Positive numerical domain index, or 'all'\n"
+    "                        for all domains (default).\n"
+    "  --verbose  -v         Show FMMUs and process data additionally.\n";
 
 /****************************************************************************/