diff --git a/frontend_tests/run-casper b/frontend_tests/run-casper
index 1774b01bb6..9684425d70 100755
--- a/frontend_tests/run-casper
+++ b/frontend_tests/run-casper
@@ -65,6 +65,8 @@ assert_provisioning_status_ok(options.force)
 
 os.chdir(ZULIP_PATH)
 
+subprocess.check_call(['node', 'node_modules/phantomjs-prebuilt/install.js'])
+
 os.makedirs('var/casper', exist_ok=True)
 
 for f in glob.glob('var/casper/casper-failure*.png'):
diff --git a/scripts/lib/node_cache.py b/scripts/lib/node_cache.py
index e11d53f6ed..7674470dcb 100644
--- a/scripts/lib/node_cache.py
+++ b/scripts/lib/node_cache.py
@@ -86,7 +86,7 @@ def do_yarn_install(target_path, yarn_args, success_stamp, stdout=None, stderr=N
     if os.environ.get('CUSTOM_CA_CERTIFICATES'):
         run([YARN_BIN, "config", "set", "cafile", os.environ['CUSTOM_CA_CERTIFICATES']],
             stdout=stdout, stderr=stderr)
-    run([YARN_BIN, "install", "--non-interactive", "--frozen-lockfile"] + yarn_args,
+    run([YARN_BIN, "install", "--non-interactive", "--frozen-lockfile", "--ignore-scripts"] + yarn_args,
         cwd=target_path, stdout=stdout, stderr=stderr)
     with open(success_stamp, 'w'):
         pass
diff --git a/version.py b/version.py
index dd98c53bac..fb40c245be 100644
--- a/version.py
+++ b/version.py
@@ -26,4 +26,4 @@ LATEST_RELEASE_ANNOUNCEMENT = "https://blog.zulip.org/2019/03/01/zulip-2-0-relea
 #   historical commits sharing the same major version, in which case a
 #   minor version bump suffices.
 
-PROVISION_VERSION = '50.0'
+PROVISION_VERSION = '51.0'