diff --git a/news/2996.trivial b/news/2996.trivial
new file mode 100644
index 00000000..dbe1006a
--- /dev/null
+++ b/news/2996.trivial
@@ -0,0 +1 @@
+Set `PIPENV_ACTIVE=1` when running `pipenv run`.  This is what `pipenv shell` already does.
\ No newline at end of file
diff --git a/pipenv/core.py b/pipenv/core.py
index 6129dc15..1b9c5ade 100644
--- a/pipenv/core.py
+++ b/pipenv/core.py
@@ -2284,6 +2284,8 @@ def do_run(command, args, three=None, python=False, pypi_mirror=None):
 
     # Ensure that virtualenv is available.
     ensure_project(three=three, python=python, validate=False, pypi_mirror=pypi_mirror)
+    # Set an environment variable, so we know we're in the environment.
+    os.environ["PIPENV_ACTIVE"] = vistir.misc.fs_str("1")
     load_dot_env()
     # Activate virtualenv under the current interpreter's environment
     inline_activate_virtual_environment()