diff --git a/processor/src/main/kotlin/org/ethereum/lists/chains/Env.kt b/processor/src/main/kotlin/org/ethereum/lists/chains/Env.kt
index b84b67cd..49f3c64a 100644
--- a/processor/src/main/kotlin/org/ethereum/lists/chains/Env.kt
+++ b/processor/src/main/kotlin/org/ethereum/lists/chains/Env.kt
@@ -26,9 +26,12 @@ val optionalFields = listOf(
     "explorers",
     "title",
     "parent",
-    "status"
+    "status",
+    "redFlags"
 )
 
+val allowedRedFlags = listOf("reusedChainId")
+
 val moshi: Moshi = Moshi.Builder().build()
 val chainAdapter: JsonAdapter<Chain> = moshi.adapter(Chain::class.java)
 
diff --git a/processor/src/main/kotlin/org/ethereum/lists/chains/Main.kt b/processor/src/main/kotlin/org/ethereum/lists/chains/Main.kt
index 82c83d9e..fee03aaa 100644
--- a/processor/src/main/kotlin/org/ethereum/lists/chains/Main.kt
+++ b/processor/src/main/kotlin/org/ethereum/lists/chains/Main.kt
@@ -272,6 +272,21 @@ fun checkChain(chainFile: File, connectRPC: Boolean) {
             throw StatusMustBeIncubatingActiveOrDeprecated()
         }
     }
+
+    jsonObject["redFlags"]?.let { redFlags ->
+        if (redFlags !is List<*>) {
+            throw RedFlagsMustBeArray()
+        }
+        redFlags.forEach {
+            if (it !is String) {
+                throw RedFlagMustBeString()
+            }
+
+            if (!allowedRedFlags.contains(it))
+                throw(InvalidRedFlags(it))
+        }
+    }
+
     jsonObject["parent"]?.let {
         if (it !is JsonObject) {
             throw ParentMustBeObject()
@@ -286,6 +301,7 @@ fun checkChain(chainFile: File, connectRPC: Boolean) {
             throw ParentHasExtraFields(extraParentFields)
         }
 
+
         val bridges = it["bridges"]
         if (bridges != null && bridges !is List<*>) {
             throw ParentBridgeNoArray()
diff --git a/processor/src/main/kotlin/org/ethereum/lists/chains/model/Exceptions.kt b/processor/src/main/kotlin/org/ethereum/lists/chains/model/Exceptions.kt
index f8503500..839c8d2b 100644
--- a/processor/src/main/kotlin/org/ethereum/lists/chains/model/Exceptions.kt
+++ b/processor/src/main/kotlin/org/ethereum/lists/chains/model/Exceptions.kt
@@ -21,6 +21,9 @@ class ExplorerMustWithHttps: Exception("Explorer have url starting with https://
 class ExplorerCannotEndInSlash: Exception("Explorer cannot have a slash on the end")
 class ExplorerStandardMustBeEIP3091OrNone: Exception("explorer standard must be 'none' or 'EIP3091'")
 class ParentHasInvalidType(type: String?): Exception("Parent has invalid type $type - only L2 or shard allowed")
+class RedFlagsMustBeArray: Exception("redFlags not an array")
+class RedFlagMustBeString: Exception("redFlag not an string")
+class InvalidRedFlags(flag: String): Exception("redFlags invalid $flag")
 class ParentMustBeObject: Exception("parent must be an object")
 class ParentMustHaveChainAndType: Exception("parent must have fields 'chain' and 'type'")
 class ParentHasExtraFields(fields: Set<String>): Exception("parent has extra field: $fields")
diff --git a/processor/src/test/kotlin/org/ethereum/lists/chains/TheChainChecker.kt b/processor/src/test/kotlin/org/ethereum/lists/chains/TheChainChecker.kt
index 6ab8ea30..e87b2f75 100644
--- a/processor/src/test/kotlin/org/ethereum/lists/chains/TheChainChecker.kt
+++ b/processor/src/test/kotlin/org/ethereum/lists/chains/TheChainChecker.kt
@@ -71,6 +71,21 @@ class TheChainChecker {
         checkChain(file, false)
     }
 
+
+    @Test(expected = RedFlagsMustBeArray::class)
+    fun shouldFailForInvalidRedFlagsNotArray() {
+        val file = getFile("invalid/invalid_redFlags/eip155-2.json")
+
+        checkChain(file, false)
+    }
+
+    @Test(expected = InvalidRedFlags::class)
+    fun shouldFailForInvalidRedFlag() {
+        val file = getFile("invalid/invalid_redFlags/eip155-3.json")
+
+        checkChain(file, false)
+    }
+
     @Test(expected = ParentHasExtraFields::class)
     fun shouldFailForParentWithExtraParentField() {
         val file = getFile("invalid/withparentextrafield/eip155-2.json")
diff --git a/processor/src/test/resources/test_chains/invalid/invalid_redFlags/eip155-2.json b/processor/src/test/resources/test_chains/invalid/invalid_redFlags/eip155-2.json
new file mode 100644
index 00000000..b2e327d6
--- /dev/null
+++ b/processor/src/test/resources/test_chains/invalid/invalid_redFlags/eip155-2.json
@@ -0,0 +1,19 @@
+{
+  "name": "Ethereum Mainnet",
+  "shortName": "eth",
+  "chain": "ETH",
+  "chainId": 2,
+  "networkId": 2,
+  "rpc": [
+    "https://mainnet.infura.io/v3/${INFURA_API_KEY}",
+    "https://api.mycryptoapi.com/eth"
+  ],
+  "faucets": [],
+  "infoURL": "https://ethereum.org",
+  "nativeCurrency": {
+    "name": "Ether",
+    "symbol": "ETH",
+    "decimals": 18
+  },
+  "redFlags": "yolo"
+}
diff --git a/processor/src/test/resources/test_chains/invalid/invalid_redFlags/eip155-3.json b/processor/src/test/resources/test_chains/invalid/invalid_redFlags/eip155-3.json
new file mode 100644
index 00000000..b1c3ff86
--- /dev/null
+++ b/processor/src/test/resources/test_chains/invalid/invalid_redFlags/eip155-3.json
@@ -0,0 +1,19 @@
+{
+  "name": "Ethereum Mainnet",
+  "shortName": "eth",
+  "chain": "ETH",
+  "chainId": 3,
+  "networkId": 3,
+  "rpc": [
+    "https://mainnet.infura.io/v3/${INFURA_API_KEY}",
+    "https://api.mycryptoapi.com/eth"
+  ],
+  "faucets": [],
+  "infoURL": "https://ethereum.org",
+  "nativeCurrency": {
+    "name": "Ether",
+    "symbol": "ETH",
+    "decimals": 18
+  },
+  "redFlags": ["yolo"]
+}
diff --git a/processor/src/test/resources/test_chains/valid/eip155-5.json b/processor/src/test/resources/test_chains/valid/eip155-5.json
index 15387bf6..2ea2fbd5 100644
--- a/processor/src/test/resources/test_chains/valid/eip155-5.json
+++ b/processor/src/test/resources/test_chains/valid/eip155-5.json
@@ -20,6 +20,9 @@
   "chainId": 5,
   "networkId": 5,
   "ens": {
-    "registry":"0x112234455c3a32fd11230c42e7bccd4a84e02010"
-  }
+    "registry": "0x112234455c3a32fd11230c42e7bccd4a84e02010"
+  },
+  "redFlags": [
+    "reusedChainId"
+  ]
 }