diff --git a/scripts/lib/node_cache.py b/scripts/lib/node_cache.py
index 3c189940c6..b58fb80a75 100644
--- a/scripts/lib/node_cache.py
+++ b/scripts/lib/node_cache.py
@@ -5,7 +5,7 @@ import hashlib
 from os.path import dirname, abspath
 
 if False:
-    from typing import Optional, List, IO, Tuple, Any
+    from typing import Optional, List, IO, Text, Tuple, Any
 
 from scripts.lib.zulip_tools import subprocess_text_output, run
 
@@ -30,16 +30,19 @@ def get_yarn_args(production):
         yarn_args = []
     return yarn_args
 
-def generate_sha1sum_node_modules(production=DEFAULT_PRODUCTION):
-    # type: (bool) -> str
+def generate_sha1sum_node_modules(setup_dir=None, production=DEFAULT_PRODUCTION):
+    # type: (Optional[Text], bool) -> str
+    if setup_dir is None:
+        setup_dir = os.path.realpath(os.getcwd())
+    PACKAGE_JSON_FILE_PATH = os.path.join(setup_dir, 'package.json')
+    YARN_LOCK_FILE_PATH = os.path.join(setup_dir, 'yarn.lock')
     sha1sum = hashlib.sha1()
-    sha1sum.update(subprocess_text_output(['cat', 'package.json']).encode('utf8'))
-    sha1sum.update(subprocess_text_output(['cat', 'yarn.lock']).encode('utf8'))
+    sha1sum.update(subprocess_text_output(['cat', PACKAGE_JSON_FILE_PATH]).encode('utf8'))
+    sha1sum.update(subprocess_text_output(['cat', YARN_LOCK_FILE_PATH]).encode('utf8'))
     sha1sum.update(subprocess_text_output([YARN_BIN, '--version']).encode('utf8'))
     sha1sum.update(subprocess_text_output(['node', '--version']).encode('utf8'))
     yarn_args = get_yarn_args(production=production)
     sha1sum.update(''.join(sorted(yarn_args)).encode('utf8'))
-
     return sha1sum.hexdigest()
 
 def setup_node_modules(production=DEFAULT_PRODUCTION, stdout=None, stderr=None, copy_modules=False,