diff --git a/tests/CrawlerProcess/sleeping.py b/tests/CrawlerProcess/sleeping.py
index 420d9d328..45479ea4f 100644
--- a/tests/CrawlerProcess/sleeping.py
+++ b/tests/CrawlerProcess/sleeping.py
@@ -14,7 +14,7 @@ class SleepingSpider(scrapy.Spider):
         from twisted.internet import reactor
 
         d = Deferred()
-        reactor.callLater(3, d.callback, None)
+        reactor.callLater(int(self.sleep), d.callback, None)
         await maybe_deferred_to_future(d)
 
 
diff --git a/tests/test_command_shell.py b/tests/test_command_shell.py
index 7d87eb62c..7918d94b2 100644
--- a/tests/test_command_shell.py
+++ b/tests/test_command_shell.py
@@ -1,3 +1,4 @@
+import os
 import sys
 from io import BytesIO
 from pathlib import Path
@@ -147,8 +148,10 @@ class InteractiveShellTest(unittest.TestCase):
             "scrapy.cmdline",
             "shell",
         )
+        env = os.environ.copy()
+        env["SCRAPY_PYTHON_SHELL"] = "python"
         logfile = BytesIO()
-        p = PopenSpawn(args, timeout=5)
+        p = PopenSpawn(args, env=env, timeout=5)
         p.logfile_read = logfile
         p.expect_exact("Available Scrapy objects")
         with MockServer() as mockserver:
diff --git a/tests/test_crawler.py b/tests/test_crawler.py
index 60b92377d..0a7f9bac8 100644
--- a/tests/test_crawler.py
+++ b/tests/test_crawler.py
@@ -525,7 +525,7 @@ class CrawlerProcessSubprocess(ScriptRunnerMixin, unittest.TestCase):
 
     def test_shutdown_graceful(self):
         sig = signal.SIGINT if sys.platform != "win32" else signal.SIGBREAK
-        args = self.get_script_args("sleeping.py")
+        args = self.get_script_args("sleeping.py", "-a", "sleep=3")
         p = PopenSpawn(args, timeout=5)
         p.expect_exact("Spider opened")
         p.expect_exact("Crawled (200)")
@@ -534,14 +534,21 @@ class CrawlerProcessSubprocess(ScriptRunnerMixin, unittest.TestCase):
         p.expect_exact("Spider closed (shutdown)")
         p.wait()
 
+    @defer.inlineCallbacks
     def test_shutdown_forced(self):
+        from twisted.internet import reactor
+
         sig = signal.SIGINT if sys.platform != "win32" else signal.SIGBREAK
-        args = self.get_script_args("sleeping.py")
+        args = self.get_script_args("sleeping.py", "-a", "sleep=10")
         p = PopenSpawn(args, timeout=5)
         p.expect_exact("Spider opened")
         p.expect_exact("Crawled (200)")
         p.kill(sig)
         p.expect_exact("shutting down gracefully")
+        # sending the second signal too fast often causes problems
+        d = defer.Deferred()
+        reactor.callLater(0.1, d.callback, None)
+        yield d
         p.kill(sig)
         p.expect_exact("forcing unclean shutdown")
         p.wait()