diff --git a/frontend_tests/run-casper b/frontend_tests/run-casper
index 8f409637bd..f19c8d0416 100755
--- a/frontend_tests/run-casper
+++ b/frontend_tests/run-casper
@@ -1,12 +1,18 @@
 #!/usr/bin/env python
 from __future__ import print_function
 import subprocess
-import requests
 import optparse
 import time
 import sys
 import os
 import glob
+try:
+    import requests
+except ImportError as e:
+    print("ImportError: {}".format(e))
+    print("You need to run the Zulip tests inside a Zulip dev environment.")
+    print("If you are using Vagrant, you can `vagrant ssh` to enter the Vagrant guest.")
+    sys.exit(1)
 
 #
 # In order to use remote casperjs debugging, pass the --remote-debug flag
diff --git a/tools/lint-all b/tools/lint-all
index c3976c95c5..dbba33ab50 100755
--- a/tools/lint-all
+++ b/tools/lint-all
@@ -7,8 +7,13 @@ import sys
 import optparse
 import subprocess
 import traceback
-
-import lister
+try:
+    import lister
+except ImportError as e:
+    print("ImportError: {}".format(e))
+    print("You need to run the Zulip linters inside a Zulip dev environment.")
+    print("If you are using Vagrant, you can `vagrant ssh` to enter the Vagrant guest.")
+    sys.exit(1)
 
 parser = optparse.OptionParser()
 parser.add_option('--full',
diff --git a/tools/test-backend b/tools/test-backend
index c85aaee126..bcff848691 100755
--- a/tools/test-backend
+++ b/tools/test-backend
@@ -6,9 +6,15 @@ import os
 import sys
 import subprocess
 
-import django
-from django.conf import settings
-from django.test.utils import get_runner
+try:
+    import django
+    from django.conf import settings
+    from django.test.utils import get_runner
+except ImportError as e:
+    print("ImportError: {}".format(e))
+    print("You need to run the Zulip tests inside a Zulip dev environment.")
+    print("If you are using Vagrant, you can `vagrant ssh` to enter the Vagrant guest.")
+    sys.exit(1)
 
 if __name__ == "__main__":
     TOOLS_DIR = os.path.dirname(os.path.abspath(__file__))