diff --git a/js/src/core.ts b/js/src/core.ts
index 90bde7a3..b9cf2d21 100644
--- a/js/src/core.ts
+++ b/js/src/core.ts
@@ -293,6 +293,9 @@ export function getEncodingNameForModel(model: TiktokenModel) {
     case "chatgpt-4o-latest":
     case "gpt-4o-realtime":
     case "gpt-4o-realtime-preview-2024-10-01":
+    case "gpt-4.1":
+    case "gpt-4.1-mini":
+    case "gpt-4.1-nano":
     {
       return "o200k_base";
     }
diff --git a/tiktoken/model_to_encoding.json b/tiktoken/model_to_encoding.json
index 6b55f317..9f48e5a8 100644
--- a/tiktoken/model_to_encoding.json
+++ b/tiktoken/model_to_encoding.json
@@ -71,5 +71,8 @@
     "o3-mini-2025-01-31": "o200k_base",
     "chatgpt-4o-latest": "o200k_base",
     "gpt-4o-realtime": "o200k_base",
-    "gpt-4o-realtime-preview-2024-10-01": "o200k_base"
+    "gpt-4o-realtime-preview-2024-10-01": "o200k_base",
+    "gpt-4.1": "o200k_base",
+    "gpt-4.1-mini": "o200k_base",
+    "gpt-4.1-nano": "o200k_base"
 }
diff --git a/wasm/src/lib.rs b/wasm/src/lib.rs
index 65b29a00..910e4dc4 100644
--- a/wasm/src/lib.rs
+++ b/wasm/src/lib.rs
@@ -436,7 +436,10 @@ export type TiktokenModel =
     | "o3-mini-2025-01-31"
     | "chatgpt-4o-latest"
     | "gpt-4o-realtime"
-    | "gpt-4o-realtime-preview-2024-10-01"
+    | "gpt-4o-realtime-preview-2024-10-01",
+    | "gpt-4.1",
+    | "gpt-4.1-mini",
+    | "gpt-4.1-nano"
 
 /**
  * @param {TiktokenModel} encoding