diff --git a/nixos/modules/installer/tools/nixos-version.sh b/nixos/modules/installer/tools/nixos-version.sh
index 0117aa1549cb..2711bc1e131e 100644
--- a/nixos/modules/installer/tools/nixos-version.sh
+++ b/nixos/modules/installer/tools/nixos-version.sh
@@ -10,7 +10,7 @@ case "$1" in
     ;;
   --json)
     cat <<EOF
-{"nixosVersion": "@version@", "nixpkgsRevision": "@revision@", "configurationRevision": "@configurationRevision@"}
+@json@
 EOF
     ;;
   *)
diff --git a/nixos/modules/installer/tools/tools.nix b/nixos/modules/installer/tools/tools.nix
index 47fa4725288d..833865e99bb3 100644
--- a/nixos/modules/installer/tools/tools.nix
+++ b/nixos/modules/installer/tools/tools.nix
@@ -49,6 +49,13 @@ let
     src = ./nixos-version.sh;
     inherit (config.system.nixos) version codeName revision;
     inherit (config.system) configurationRevision;
+    json = builtins.toJSON ({
+      nixosVersion = config.system.nixos.version;
+    } // optionalAttrs (config.system.nixos.revision != null) {
+      nixpkgsRevision = config.system.nixos.revision;
+    } // optionalAttrs (config.system.configurationRevision != null) {
+      configurationRevision = config.system.configurationRevision;
+    });
   };
 
   nixos-enter = makeProg {