diff --git a/src/libcmd/command.hh b/src/libcmd/command.hh
index 874ca3249..b7a87dad0 100644
--- a/src/libcmd/command.hh
+++ b/src/libcmd/command.hh
@@ -18,6 +18,7 @@ class EvalState;
 struct Pos;
 class Store;
 
+static constexpr Command::Category catHelp = -1;
 static constexpr Command::Category catSecondary = 100;
 static constexpr Command::Category catUtility = 101;
 static constexpr Command::Category catNixInstallation = 102;
diff --git a/src/nix/main.cc b/src/nix/main.cc
index 5981028f7..ffe558ee8 100644
--- a/src/nix/main.cc
+++ b/src/nix/main.cc
@@ -65,6 +65,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
     NixArgs() : MultiCommand(RegisterCommand::getCommandsFor({})), MixCommonArgs("nix")
     {
         categories.clear();
+        categories[catHelp] = "Help commands";
         categories[Command::catDefault] = "Main commands";
         categories[catSecondary] = "Infrequently used commands";
         categories[catUtility] = "Utility/scripting commands";
@@ -255,6 +256,8 @@ struct CmdHelp : Command
           ;
     }
 
+    Category category() override { return catHelp; }
+
     void run() override
     {
         assert(parent);
@@ -280,6 +283,8 @@ struct CmdHelpStores : Command
           ;
     }
 
+    Category category() override { return catHelp; }
+
     void run() override
     {
         showHelp({"help-stores"}, getNixArgs(*this));