diff --git a/mcp-core/src/test/java/io/modelcontextprotocol/client/AbstractMcpAsyncClientTests.java b/mcp-core/src/test/java/io/modelcontextprotocol/client/AbstractMcpAsyncClientTests.java
index 859dc5f82..57a223ea2 100644
--- a/mcp-core/src/test/java/io/modelcontextprotocol/client/AbstractMcpAsyncClientTests.java
+++ b/mcp-core/src/test/java/io/modelcontextprotocol/client/AbstractMcpAsyncClientTests.java
@@ -673,7 +673,7 @@ void testInitializeWithElicitationCapability() {
 	@Test
 	void testInitializeWithAllCapabilities() {
 		var capabilities = ClientCapabilities.builder()
-			.experimental(Map.of("feature", "test"))
+			.experimental(Map.of("feature", Map.of("featureFlag", true)))
 			.roots(true)
 			.sampling()
 			.build();