diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 966b0463c2..0f0d031f35 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -20,6 +20,7 @@ from .authproxy import JSONRPCException
 from .util import (
     append_config,
     assert_equal,
+    delete_cookie_file,
     get_rpc_proxy,
     rpc_url,
     wait_until,
@@ -116,6 +117,10 @@ class TestNode():
             extra_args = self.extra_args
         if stderr is None:
             stderr = self.stderr
+        # Delete any existing cookie file -- if such a file exists (eg due to
+        # unclean shutdown), it will get overwritten anyway by bitcoind, and
+        # potentially interfere with our attempt to authenticate
+        delete_cookie_file(self.datadir)
         self.process = subprocess.Popen(self.args + extra_args, stderr=stderr, *args, **kwargs)
         self.running = True
         self.log.debug("bitcoind started, waiting for RPC to come up")
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index a24a2ec4f5..f22322fbbc 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -332,6 +332,12 @@ def get_auth_cookie(datadir):
         raise ValueError("No RPC credentials")
     return user, password
 
+# If a cookie file exists in the given datadir, delete it.
+def delete_cookie_file(datadir):
+    if os.path.isfile(os.path.join(datadir, "regtest", ".cookie")):
+        logger.debug("Deleting leftover cookie file")
+        os.remove(os.path.join(datadir, "regtest", ".cookie"))
+
 def get_bip9_status(node, key):
     info = node.getblockchaininfo()
     return info['bip9_softforks'][key]