diff --git a/src/nix-env/help.txt b/src/nix-env/help.txt
index 72fc4f13ed..d20c366cb7 100644
--- a/src/nix-env/help.txt
+++ b/src/nix-env/help.txt
@@ -1,4 +1,4 @@
-nix-env [OPTIONS...] [ARGUMENTS...]
+Usage: nix-env [OPTIONS...] [ARGUMENTS...]
 
 `nix-env' is a tool to manipulate Nix user environments.
 
diff --git a/src/nix-hash/help.txt b/src/nix-hash/help.txt
index 082cc7571c..6c166f4995 100644
--- a/src/nix-hash/help.txt
+++ b/src/nix-hash/help.txt
@@ -1,4 +1,4 @@
-nix-hash [OPTIONS...] [FILES...]
+Usage: nix-hash [OPTIONS...] [FILES...]
 
 `nix-hash' computes and prints cryptographic hashes for the specified
 files.
diff --git a/src/nix-instantiate/help.txt b/src/nix-instantiate/help.txt
index 5b9d82aa99..45607b71af 100644
--- a/src/nix-instantiate/help.txt
+++ b/src/nix-instantiate/help.txt
@@ -1,4 +1,4 @@
-nix-instantiate [OPTIONS...] [FILES...]
+Usage: nix-instantiate [OPTIONS...] [FILES...]
 
 `nix-instantiate' turns Nix expressions into store derivations. 
 
diff --git a/src/nix-store/help.txt b/src/nix-store/help.txt
index 074745813f..0e04926af7 100644
--- a/src/nix-store/help.txt
+++ b/src/nix-store/help.txt
@@ -1,4 +1,4 @@
-nix-store [OPTIONS...] [ARGUMENTS...]
+Usage: nix-store [OPTIONS...] [ARGUMENTS...]
 
 `nix-store' is a tool to manipulate the Nix store.