diff --git a/src/nix/develop.cc b/src/nix/develop.cc
index c20b9f272..f22335023 100644
--- a/src/nix/develop.cc
+++ b/src/nix/develop.cc
@@ -392,6 +392,12 @@ struct CmdDevelop : Common, MixEnvironment
             .handler = {&phase},
         });
 
+        addFlag({
+            .longName = "unpack",
+            .description = "Run the `unpack` phase.",
+            .handler = {&phase, {"unpack"}},
+        });
+
         addFlag({
             .longName = "configure",
             .description = "Run the `configure` phase.",
diff --git a/src/nix/develop.md b/src/nix/develop.md
index c86c4872b..1f214966a 100644
--- a/src/nix/develop.md
+++ b/src/nix/develop.md
@@ -29,6 +29,7 @@ R""(
 * Run a particular build phase directly:
 
   ```console
+  # nix develop --unpack
   # nix develop --configure
   # nix develop --build
   # nix develop --check