diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 69efe8f5..8d572e9c 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "2.40.0"
+  ".": "2.40.1"
 }
\ No newline at end of file
diff --git a/.stats.yml b/.stats.yml
index 82f3ca09..b3a3f2f6 100644
--- a/.stats.yml
+++ b/.stats.yml
@@ -1,4 +1,4 @@
 configured_endpoints: 116
-openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/anthropic/anthropic-3368ac7f3ae66514b5e46832c85918a6ea36e95c0efe98e0955c4455dd57a6b8.yml
-openapi_spec_hash: 255cf18e4e19ab1ab5cdc52717abe558
+openapi_spec_url: https://storage.googleapis.com/stainless-sdk-openapi-specs/anthropic/anthropic-5ce93251152bd7c4c288dacdf5a445383825ba50bc472ff9e9821ee9455e3564.yml
+openapi_spec_hash: 989d596f7660ce55a7cea748a9292b45
 config_hash: 44acd8a997dff056931fb4466201cdeb
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ab6a837b..28c2e516 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,14 @@
 # Changelog
 
+## 2.40.1 (2026-06-09)
+
+Full Changelog: [v2.40.0...v2.40.1](https://github.com/anthropics/anthropic-sdk-java/compare/v2.40.0...v2.40.1)
+
+### Bug Fixes
+
+* **api:** add `frontier_llm` refusal category ([1627fd3](https://github.com/anthropics/anthropic-sdk-java/commit/1627fd3561cb8594d81e9e384e1191faf27d53d3))
+* **client:** bad `toParam` conversion ([e3b5adb](https://github.com/anthropics/anthropic-sdk-java/commit/e3b5adbc64eed075f802082a647b6cb1fd055ac9))
+
 ## 2.40.0 (2026-06-09)
 
 Full Changelog: [v2.39.0...v2.40.0](https://github.com/anthropics/anthropic-sdk-java/compare/v2.39.0...v2.40.0)
diff --git a/README.md b/README.md
index 4190b27e..1d1082a7 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ Full documentation is available at **[platform.claude.com/docs/en/api/sdks/java]
 ### Gradle
 
 ```kotlin
-implementation("com.anthropic:anthropic-java:2.40.0")
+implementation("com.anthropic:anthropic-java:2.40.1")
 ```
 
 ### Maven
@@ -24,7 +24,7 @@ implementation("com.anthropic:anthropic-java:2.40.0")
 <dependency>
   <groupId>com.anthropic</groupId>
   <artifactId>anthropic-java</artifactId>
-  <version>2.40.0</version>
+  <version>2.40.1</version>
 </dependency>
 ```
 
diff --git a/anthropic-java-core/src/main/kotlin/com/anthropic/models/beta/messages/BetaRefusalStopDetails.kt b/anthropic-java-core/src/main/kotlin/com/anthropic/models/beta/messages/BetaRefusalStopDetails.kt
index 9cc734fb..1afefc04 100644
--- a/anthropic-java-core/src/main/kotlin/com/anthropic/models/beta/messages/BetaRefusalStopDetails.kt
+++ b/anthropic-java-core/src/main/kotlin/com/anthropic/models/beta/messages/BetaRefusalStopDetails.kt
@@ -526,6 +526,8 @@ private constructor(
 
             @JvmField val BIO = of("bio")
 
+            @JvmField val FRONTIER_LLM = of("frontier_llm")
+
             @JvmField val REASONING_EXTRACTION = of("reasoning_extraction")
 
             @JvmStatic fun of(value: String) = Category(JsonField.of(value))
@@ -535,6 +537,7 @@ private constructor(
         enum class Known {
             CYBER,
             BIO,
+            FRONTIER_LLM,
             REASONING_EXTRACTION,
         }
 
@@ -550,6 +553,7 @@ private constructor(
         enum class Value {
             CYBER,
             BIO,
+            FRONTIER_LLM,
             REASONING_EXTRACTION,
             /** An enum member indicating that [Category] was instantiated with an unknown value. */
             _UNKNOWN,
@@ -566,6 +570,7 @@ private constructor(
             when (this) {
                 CYBER -> Value.CYBER
                 BIO -> Value.BIO
+                FRONTIER_LLM -> Value.FRONTIER_LLM
                 REASONING_EXTRACTION -> Value.REASONING_EXTRACTION
                 else -> Value._UNKNOWN
             }
@@ -583,6 +588,7 @@ private constructor(
             when (this) {
                 CYBER -> Known.CYBER
                 BIO -> Known.BIO
+                FRONTIER_LLM -> Known.FRONTIER_LLM
                 REASONING_EXTRACTION -> Known.REASONING_EXTRACTION
                 else -> throw AnthropicInvalidDataException("Unknown Category: $value")
             }
diff --git a/anthropic-java-core/src/main/kotlin/com/anthropic/models/messages/RefusalStopDetails.kt b/anthropic-java-core/src/main/kotlin/com/anthropic/models/messages/RefusalStopDetails.kt
index 3a064a12..5566919c 100644
--- a/anthropic-java-core/src/main/kotlin/com/anthropic/models/messages/RefusalStopDetails.kt
+++ b/anthropic-java-core/src/main/kotlin/com/anthropic/models/messages/RefusalStopDetails.kt
@@ -286,6 +286,8 @@ private constructor(
 
             @JvmField val BIO = of("bio")
 
+            @JvmField val FRONTIER_LLM = of("frontier_llm")
+
             @JvmField val REASONING_EXTRACTION = of("reasoning_extraction")
 
             @JvmStatic fun of(value: String) = Category(JsonField.of(value))
@@ -295,6 +297,7 @@ private constructor(
         enum class Known {
             CYBER,
             BIO,
+            FRONTIER_LLM,
             REASONING_EXTRACTION,
         }
 
@@ -310,6 +313,7 @@ private constructor(
         enum class Value {
             CYBER,
             BIO,
+            FRONTIER_LLM,
             REASONING_EXTRACTION,
             /** An enum member indicating that [Category] was instantiated with an unknown value. */
             _UNKNOWN,
@@ -326,6 +330,7 @@ private constructor(
             when (this) {
                 CYBER -> Value.CYBER
                 BIO -> Value.BIO
+                FRONTIER_LLM -> Value.FRONTIER_LLM
                 REASONING_EXTRACTION -> Value.REASONING_EXTRACTION
                 else -> Value._UNKNOWN
             }
@@ -343,6 +348,7 @@ private constructor(
             when (this) {
                 CYBER -> Known.CYBER
                 BIO -> Known.BIO
+                FRONTIER_LLM -> Known.FRONTIER_LLM
                 REASONING_EXTRACTION -> Known.REASONING_EXTRACTION
                 else -> throw AnthropicInvalidDataException("Unknown Category: $value")
             }
diff --git a/build.gradle.kts b/build.gradle.kts
index dc88cd95..07b458e3 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -8,7 +8,7 @@ repositories {
 
 allprojects {
     group = "com.anthropic"
-    version = "2.40.0" // x-release-please-version
+    version = "2.40.1" // x-release-please-version
 }
 
 subprojects {