diff --git a/bin/compile b/bin/compile
index a8bd024ef645d652b1add0b6933c1fc6f3614d6d..858e7065ee7fa22545613d29ce7cf4eddd393baa 100755
--- a/bin/compile
+++ b/bin/compile
@@ -48,7 +48,7 @@ export PATH=$PATH:$ROOT_DIR/vendor/:$ROOT_DIR/vendor/pip-pop
 
 # Sanitizing environment variables.
 unset GIT_DIR PYTHONHOME PYTHONPATH
-unset RECEIVE_DATA RUN_KEY BUILD_INFO DEPLOY LOG_TOKEN DYNO
+unset RECEIVE_DATA RUN_KEY BUILD_INFO DEPLOY LOG_TOKEN
 unset CYTOKINE_LOG_FILE GEM_PATH
 
 # Syntax sugar.
diff --git a/bin/utils b/bin/utils
index c8785d0fa8f0bcfcb3648a1fb970bbc0eb773f99..8d037fe32f27dfaba9aea78145654e8029282caf 100755
--- a/bin/utils
+++ b/bin/utils
@@ -88,7 +88,7 @@ deep-rm() {
 sub-env() {
 
   WHITELIST=${2:-''}
-  BLACKLIST=${3:-'^(GIT_DIR|PYTHONHOME|LD_LIBRARY_PATH|LIBRARY_PATH|PATH)$'}
+  BLACKLIST=${3:-'^(GIT_DIR|STACK|PYTHONHOME|LD_LIBRARY_PATH|LIBRARY_PATH|PATH)$'}
 
   # Python-specific variables.
   export PYHONHOME=$BUILD_DIR/.heroku/python