diff --git a/src/validation.cpp b/src/validation.cpp
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -725,16 +725,9 @@
             extraFlags |= SCRIPT_ENABLE_SCHNORR;
         }
 
-        // Check inputs based on the set of flags we activate.
-        uint32_t scriptVerifyFlags = STANDARD_SCRIPT_VERIFY_FLAGS;
-        if (!config.GetChainParams().RequireStandard()) {
-            scriptVerifyFlags =
-                SCRIPT_ENABLE_SIGHASH_FORKID |
-                gArgs.GetArg("-promiscuousmempoolflags", scriptVerifyFlags);
-        }
-
         // Make sure whatever we need to activate is actually activated.
-        scriptVerifyFlags |= extraFlags;
+        const uint32_t scriptVerifyFlags =
+            STANDARD_SCRIPT_VERIFY_FLAGS | extraFlags;
 
         // Check against previous transactions. This is done last to help
         // prevent CPU exhaustion denial-of-service attacks.
@@ -766,28 +759,9 @@
         if (!CheckInputsFromMempoolAndCache(tx, state, view, pool,
                                             currentBlockScriptVerifyFlags, true,
                                             txdata)) {
-            // If we're using promiscuousmempoolflags, we may hit this normally.
-            // Check if current block has some flags that scriptVerifyFlags does
-            // not before printing an ominous warning.
-            if (!(~scriptVerifyFlags & currentBlockScriptVerifyFlags)) {
-                return error(
-                    "%s: BUG! PLEASE REPORT THIS! ConnectInputs failed against "
-                    "MANDATORY but not STANDARD flags %s, %s",
-                    __func__, txid.ToString(), FormatStateMessage(state));
-            }
-
-            if (!CheckInputs(tx, state, view, true,
-                             MANDATORY_SCRIPT_VERIFY_FLAGS | extraFlags, true,
-                             false, txdata)) {
-                return error(
-                    "%s: ConnectInputs failed against MANDATORY but not "
-                    "STANDARD flags due to promiscuous mempool %s, %s",
-                    __func__, txid.ToString(), FormatStateMessage(state));
-            }
-
-            LogPrintf("Warning: -promiscuousmempool flags set to not include "
-                      "currently enforced soft forks, this may break mining or "
-                      "otherwise cause instability!\n");
+            return error("%s: BUG! PLEASE REPORT THIS! CheckInputs failed "
+                         "against latest-block but not STANDARD flags %s, %s",
+                         __func__, txid.ToString(), FormatStateMessage(state));
         }
 
         if (test_accept) {
diff --git a/test/functional/feature_cltv.py b/test/functional/feature_cltv.py
--- a/test/functional/feature_cltv.py
+++ b/test/functional/feature_cltv.py
@@ -97,8 +97,7 @@
 class BIP65Test(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 1
-        self.extra_args = [
-            ['-promiscuousmempoolflags=1', '-whitelist=127.0.0.1']]
+        self.extra_args = [['-whitelist=127.0.0.1']]
         self.setup_clean_chain = True
 
     def run_test(self):
@@ -179,11 +178,14 @@
         # This block is valid
         assert_equal(self.nodes[0].getbestblockhash(), block.hash)
 
-        # We show that this tx is valid except for CLTV by getting it
-        # accepted to the mempool (which we can achieve with
-        # -promiscuousmempoolflags).
-        self.nodes[0].p2p.send_and_ping(msg_tx(spendtx))
-        assert spendtx.hash in self.nodes[0].getrawmempool()
+        # We show that this tx is invalid due to CLTV by getting it
+        # rejected from the mempool for exactly that reason.
+        assert_equal(
+            [{'txid': spendtx.hash, 'allowed': False,
+                'reject-reason': '64: non-mandatory-script-verify-flag (Negative locktime)'}],
+            self.nodes[0].testmempoolaccept(
+                rawtxs=[spendtx.serialize().hex()], allowhighfees=True)
+        )
 
         rejectedtx_signed = self.nodes[0].signrawtransactionwithwallet(
             ToHex(spendtx))
diff --git a/test/functional/feature_dersig.py b/test/functional/feature_dersig.py
--- a/test/functional/feature_dersig.py
+++ b/test/functional/feature_dersig.py
@@ -8,7 +8,7 @@
 """
 
 from test_framework.blocktools import create_block, create_coinbase
-from test_framework.messages import CTransaction, FromHex, msg_block
+from test_framework.messages import CTransaction, FromHex, msg_block, ToHex
 from test_framework.mininode import (
     mininode_lock,
     network_thread_start,
@@ -56,8 +56,7 @@
 class BIP66Test(BitcoinTestFramework):
     def set_test_params(self):
         self.num_nodes = 1
-        self.extra_args = [
-            ['-promiscuousmempoolflags=1', '-whitelist=127.0.0.1']]
+        self.extra_args = [['-whitelist=127.0.0.1']]
         self.setup_clean_chain = True
 
     def run_test(self):
@@ -103,7 +102,16 @@
         unDERify(spendtx)
         spendtx.rehash()
 
-        # Now we verify that a block with this transaction is invalid.
+        # First we show that this tx is valid except for DERSIG by getting it
+        # rejected from the mempool for exactly that reason.
+        assert_equal(
+            [{'txid': spendtx.hash, 'allowed': False,
+                'reject-reason': '16: mandatory-script-verify-flag-failed (Non-canonical DER signature)'}],
+            self.nodes[0].testmempoolaccept(
+                rawtxs=[ToHex(spendtx)], allowhighfees=True)
+        )
+
+        # Now we verify that a block with this transaction is also invalid.
         block.vtx.append(spendtx)
         block.hashMerkleRoot = block.calc_merkle_root()
         block.rehash()
diff --git a/test/lint/check-doc.py b/test/lint/check-doc.py
--- a/test/lint/check-doc.py
+++ b/test/lint/check-doc.py
@@ -37,7 +37,6 @@
                         '-h',
                         '-help',
                         '-parkdeepreorg',
-                        '-promiscuousmempoolflags',
                         '-replayprotectionactivationtime',
                         '-rpcssl',
                         '-socks',