diff --git a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/jackson2/StdConverters.java b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/jackson2/StdConverters.java
index 4ce6223cf43..b544f267933 100644
--- a/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/jackson2/StdConverters.java
+++ b/oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/jackson2/StdConverters.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -50,16 +50,7 @@ static final class ClientAuthenticationMethodConverter extends StdConverter<Json
 		@Override
 		public ClientAuthenticationMethod convert(JsonNode jsonNode) {
 			String value = JsonNodeUtils.findStringValue(jsonNode, "value");
-			if (ClientAuthenticationMethod.CLIENT_SECRET_BASIC.getValue().equalsIgnoreCase(value)) {
-				return ClientAuthenticationMethod.CLIENT_SECRET_BASIC;
-			}
-			if (ClientAuthenticationMethod.CLIENT_SECRET_POST.getValue().equalsIgnoreCase(value)) {
-				return ClientAuthenticationMethod.CLIENT_SECRET_POST;
-			}
-			if (ClientAuthenticationMethod.NONE.getValue().equalsIgnoreCase(value)) {
-				return ClientAuthenticationMethod.NONE;
-			}
-			return null;
+			return ClientAuthenticationMethod.valueOf(value);
 		}
 
 	}
diff --git a/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/jackson2/StdConvertersTests.java b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/jackson2/StdConvertersTests.java
new file mode 100644
index 00000000000..2cee9a1b540
--- /dev/null
+++ b/oauth2/oauth2-client/src/test/java/org/springframework/security/oauth2/client/jackson2/StdConvertersTests.java
@@ -0,0 +1,53 @@
+/*
+ * Copyright 2002-2025 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.
+ */
+
+package org.springframework.security.oauth2.client.jackson2;
+
+import java.util.stream.Stream;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.JsonNodeFactory;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.fasterxml.jackson.databind.util.StdConverter;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import org.springframework.security.oauth2.core.ClientAuthenticationMethod;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class StdConvertersTests {
+
+	private final StdConverter<JsonNode, ClientAuthenticationMethod> clientAuthenticationMethodConverter = new StdConverters.ClientAuthenticationMethodConverter();
+
+	@ParameterizedTest
+	@MethodSource("convertWhenClientAuthenticationMethodConvertedThenDeserializes")
+	void convertWhenClientAuthenticationMethodConvertedThenDeserializes(String clientAuthenticationMethod) {
+		ObjectNode jsonNode = JsonNodeFactory.instance.objectNode();
+		jsonNode.put("value", clientAuthenticationMethod);
+		ClientAuthenticationMethod actual = this.clientAuthenticationMethodConverter.convert(jsonNode);
+		assertThat(actual.getValue()).isEqualTo(clientAuthenticationMethod);
+	}
+
+	static Stream<Arguments> convertWhenClientAuthenticationMethodConvertedThenDeserializes() {
+		return Stream.of(Arguments.of(ClientAuthenticationMethod.CLIENT_SECRET_BASIC.getValue()),
+				Arguments.of(ClientAuthenticationMethod.CLIENT_SECRET_POST.getValue()),
+				Arguments.of(ClientAuthenticationMethod.PRIVATE_KEY_JWT.getValue()),
+				Arguments.of(ClientAuthenticationMethod.NONE.getValue()), Arguments.of("custom_method"));
+	}
+
+}