diff --git a/src/nix/flake-show.md b/src/nix/flake-show.md
index 1a42c44a0..e484cf47e 100644
--- a/src/nix/flake-show.md
+++ b/src/nix/flake-show.md
@@ -35,4 +35,7 @@ specified by flake reference *flake-url*. These are the top-level
 attributes in the `outputs` of the flake, as well as lower-level
 attributes for some standard outputs (e.g. `packages` or `checks`).
 
+With `--json`, the output is in a JSON representation suitable for automatic
+processing by other tools.
+
 )""
diff --git a/tests/flakes.sh b/tests/flakes.sh
index 9e1b5b508..1bce4e4bd 100644
--- a/tests/flakes.sh
+++ b/tests/flakes.sh
@@ -386,12 +386,14 @@ git -C $templatesDir commit -m 'Initial'
 
 nix flake check templates
 nix flake show templates
+nix flake show templates --json | jq
 
 (cd $flake7Dir && nix flake init)
 (cd $flake7Dir && nix flake init) # check idempotence
 git -C $flake7Dir add flake.nix
 nix flake check $flake7Dir
 nix flake show $flake7Dir
+nix flake show $flake7Dir --json | jq
 git -C $flake7Dir commit -a -m 'Initial'
 
 # Test 'nix flake new'.