diff --git a/test/functional/rpc_fundrawtransaction.py b/test/functional/rpc_fundrawtransaction.py
--- a/test/functional/rpc_fundrawtransaction.py
+++ b/test/functional/rpc_fundrawtransaction.py
@@ -14,6 +14,7 @@
     assert_greater_than_or_equal,
     assert_raises_rpc_error,
     connect_nodes_bi,
+    find_vout_for_address,
 )
 
 
@@ -73,6 +74,13 @@
         self.nodes[3].importpubkey(watchonly_pubkey, "", True)
         watchonly_txid = self.nodes[0].sendtoaddress(
             watchonly_address, watchonly_amount)
+
+        # Lock UTXO so nodes[0] doesn't accidentally spend it
+        watchonly_vout = find_vout_for_address(
+            self.nodes[0], watchonly_txid, watchonly_address)
+        self.nodes[0].lockunspent(
+            False, [{"txid": watchonly_txid, "vout": watchonly_vout}])
+
         self.nodes[0].sendtoaddress(
             self.nodes[3].getnewaddress(), watchonly_amount / 10)
 
@@ -488,6 +496,10 @@
         connect_nodes_bi(self.nodes[1], self.nodes[2])
         connect_nodes_bi(self.nodes[0], self.nodes[2])
         connect_nodes_bi(self.nodes[0], self.nodes[3])
+        # Again lock the watchonly UTXO or nodes[0] may spend it, because
+        # lockunspent is memory-only and thus lost on restart
+        self.nodes[0].lockunspent(
+            False, [{"txid": watchonly_txid, "vout": watchonly_vout}])
         self.sync_all()
 
         # drain the keypool
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -633,3 +633,16 @@
         txid = node.sendrawtransaction(signresult["hex"], True)
         txids.append(txid)
     return txids
+
+
+def find_vout_for_address(node, txid, addr):
+    """
+    Locate the vout index of the given transaction sending to the
+    given address. Raises runtime error exception if not found.
+    """
+    tx = node.getrawtransaction(txid, True)
+    for i in range(len(tx["vout"])):
+        if any([addr == a for a in tx["vout"][i]["scriptPubKey"]["addresses"]]):
+            return i
+    raise RuntimeError(
+        "Vout not found for address: txid={}, addr={}".format(txid, addr))