diff --git a/test/functional/test_framework/test_node.py b/test/functional/test_framework/test_node.py
index 19db11d8a..f6e487129 100755
--- a/test/functional/test_framework/test_node.py
+++ b/test/functional/test_framework/test_node.py
@@ -17,6 +17,7 @@ import time
 from .authproxy import JSONRPCException
 from .util import (
     assert_equal,
+    delete_cookie_file,
     get_rpc_proxy,
     rpc_url,
     wait_until,
@@ -98,6 +99,10 @@ 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 538ae7691..ead1f844f 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -319,6 +319,12 @@ 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]