diff --git a/bin/post_compile b/bin/post_compile
index 16e00622a..b628634bc 100755
--- a/bin/post_compile
+++ b/bin/post_compile
@@ -23,8 +23,6 @@ source $BIN_DIR/utils
 # Only variables that are rarely changed and not site-specific should
 # be set here. Set everything else using Heroku's CLI / dashboard.
 
-set-env IS_HEROKU 1
-
 # Override the hostname that is displayed in New Relic, so the Dyno name
 # (eg "web.1") is shown, rather than "Dynamic Hostname". $DYNO is quoted
 # so that it's expanded at runtime on each dyno, rather than now.
diff --git a/treeherder/config/settings.py b/treeherder/config/settings.py
index 9b4b6eab4..77ad8ad2f 100644
--- a/treeherder/config/settings.py
+++ b/treeherder/config/settings.py
@@ -631,7 +631,7 @@ KEY_PREFIX = TREEHERDER_MEMCACHED_KEY_PREFIX
 # This code handles the memcachier service on heroku.
 # TODO: Stop special-casing Heroku and use newer best practices from:
 # https://www.memcachier.com/documentation#django.
-if env.bool('IS_HEROKU', default=False):
+if 'DYNO' in env:
     # Prefs taken from:
     # https://github.com/rdegges/django-heroku-memcacheify/blob/v1.0.0/memcacheify.py#L30-L39
     CACHES['default'].update({