diff --git a/apisix/plugins/limit-req.lua b/apisix/plugins/limit-req.lua
index 6c5b856217cb..dd3c1dcf8fae 100644
--- a/apisix/plugins/limit-req.lua
+++ b/apisix/plugins/limit-req.lua
@@ -17,7 +17,7 @@
 local limit_req_new                     = require("resty.limit.req").new
 local core                              = require("apisix.core")
 local redis_schema                      = require("apisix.utils.redis-schema")
-local policy_to_additional_properties   = redis_schema.schema
+local policy_to_additional_properties   = core.table.deepcopy(redis_schema.schema)
 local plugin_name                       = "limit-req"
 local sleep                             = core.sleep
 local apisix_plugin                     = require("apisix.plugin")
diff --git a/apisix/utils/redis-schema.lua b/apisix/utils/redis-schema.lua
index 0a884ca81620..991919a2a9d5 100644
--- a/apisix/utils/redis-schema.lua
+++ b/apisix/utils/redis-schema.lua
@@ -15,6 +15,8 @@
 -- limitations under the License.
 --
 
+local core = require("apisix.core")
+
 local policy_to_additional_properties = {
     redis = {
         properties = {
@@ -86,12 +88,14 @@ local policy_to_additional_properties = {
     },
 }
 
-local limit_conn_redis_cluster_schema = policy_to_additional_properties["redis-cluster"]
+local limit_conn_redis_cluster_schema =
+    core.table.deepcopy(policy_to_additional_properties["redis-cluster"])
 limit_conn_redis_cluster_schema.properties.key_ttl = {
     type = "integer", default = 3600,
 }
 
-local limit_conn_redis_schema = policy_to_additional_properties["redis"]
+local limit_conn_redis_schema =
+    core.table.deepcopy(policy_to_additional_properties["redis"])
 limit_conn_redis_schema.properties.key_ttl = {
     type = "integer", default = 3600,
 }
diff --git a/t/utils/redis-schema.t b/t/utils/redis-schema.t
new file mode 100644
index 000000000000..493aedcb9446
--- /dev/null
+++ b/t/utils/redis-schema.t
@@ -0,0 +1,154 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You under the Apache License, Version 2.0
+# (the "License"); you may not use this file except in compliance with
+# the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+use t::APISIX 'no_plan';
+
+repeat_each(1);
+no_long_string();
+no_root_location();
+
+add_block_preprocessor(sub {
+    my ($block) = @_;
+
+    if (!defined $block->request) {
+        $block->set_value("request", "GET /t");
+    }
+
+});
+
+run_tests();
+
+__DATA__
+
+=== TEST 1: limit-count/limit-req validation must not pick up limit-conn's key_ttl
+--- config
+    location /t {
+        content_by_lua_block {
+            -- limit-conn extends the shared redis/redis-cluster schemas with
+            -- key_ttl. Load it first so that any leak of key_ttl into the
+            -- shared tables of apisix.utils.redis-schema would be visible
+            -- to the other rate limiting plugins below.
+            require("apisix.plugins.limit-conn")
+
+            local cases = {
+                {
+                    plugin = "limit-count",
+                    conf = {
+                        count = 2,
+                        time_window = 60,
+                        policy = "redis",
+                        redis_host = "127.0.0.1",
+                    },
+                },
+                {
+                    plugin = "limit-count",
+                    conf = {
+                        count = 2,
+                        time_window = 60,
+                        policy = "redis-cluster",
+                        redis_cluster_nodes = {"127.0.0.1:5000", "127.0.0.1:5001"},
+                        redis_cluster_name = "redis-cluster-1",
+                    },
+                },
+                {
+                    plugin = "limit-req",
+                    conf = {
+                        rate = 1,
+                        burst = 0,
+                        key = "remote_addr",
+                        policy = "redis",
+                        redis_host = "127.0.0.1",
+                    },
+                },
+                {
+                    plugin = "limit-req",
+                    conf = {
+                        rate = 1,
+                        burst = 0,
+                        key = "remote_addr",
+                        policy = "redis-cluster",
+                        redis_cluster_nodes = {"127.0.0.1:5000", "127.0.0.1:5001"},
+                        redis_cluster_name = "redis-cluster-1",
+                    },
+                },
+            }
+
+            for _, case in ipairs(cases) do
+                local plugin = require("apisix.plugins." .. case.plugin)
+                local ok, err = plugin.check_schema(case.conf)
+                if not ok then
+                    ngx.say(err)
+                elseif case.conf.key_ttl ~= nil then
+                    ngx.say(case.plugin, " ", case.conf.policy,
+                            " got key_ttl: ", case.conf.key_ttl)
+                else
+                    ngx.say("passed")
+                end
+            end
+            ngx.say("done")
+        }
+    }
+--- response_body
+passed
+passed
+passed
+passed
+done
+
+
+
+=== TEST 2: limit-conn still defaults key_ttl to 3600 and honors an explicit value
+--- config
+    location /t {
+        content_by_lua_block {
+            local plugin = require("apisix.plugins.limit-conn")
+
+            local conf = {
+                conn = 1,
+                burst = 0,
+                default_conn_delay = 0.1,
+                key = "remote_addr",
+                policy = "redis",
+                redis_host = "127.0.0.1",
+            }
+            local ok, err = plugin.check_schema(conf)
+            if not ok then
+                ngx.say(err)
+                return
+            end
+            ngx.say(conf.key_ttl)
+
+            conf = {
+                conn = 1,
+                burst = 0,
+                default_conn_delay = 0.1,
+                key = "remote_addr",
+                policy = "redis-cluster",
+                redis_cluster_nodes = {"127.0.0.1:5000", "127.0.0.1:5001"},
+                redis_cluster_name = "redis-cluster-1",
+                key_ttl = 60,
+            }
+            ok, err = plugin.check_schema(conf)
+            if not ok then
+                ngx.say(err)
+                return
+            end
+            ngx.say(conf.key_ttl)
+        }
+    }
+--- response_body
+3600
+60