diff --git a/mcp-core/src/main/java/io/modelcontextprotocol/modern/server/SubscriptionsFeature.java b/mcp-core/src/main/java/io/modelcontextprotocol/modern/server/SubscriptionsFeature.java
index 3e815da23..cc7965002 100644
--- a/mcp-core/src/main/java/io/modelcontextprotocol/modern/server/SubscriptionsFeature.java
+++ b/mcp-core/src/main/java/io/modelcontextprotocol/modern/server/SubscriptionsFeature.java
@@ -71,15 +71,18 @@ public Set<String> methods() {
 
 	@Override
 	public Mono<McpAsyncResponse<Result>> handle(McpRequestContext ctx, Object params) {
+		// The JSON creator fills a missing filter in, so check the raw params.
+		if (!(params instanceof Map<?, ?> map) || map.get("notifications") == null) {
+			return Mono.error(McpException.invalidParams("params.notifications is required"));
+		}
 		SubscriptionsListenRequest request;
 		try {
-			request = params == null ? null : this.jsonMapper.convertValue(params, SubscriptionsListenRequest.class);
+			request = this.jsonMapper.convertValue(params, SubscriptionsListenRequest.class);
 		}
 		catch (RuntimeException ex) {
 			return Mono.error(McpException.invalidParams("Malformed SubscriptionsListenRequest"));
 		}
-		SubscriptionFilter requested = request == null || request.notifications() == null ? SubscriptionFilter.EMPTY
-				: request.notifications();
+		SubscriptionFilter requested = request.notifications();
 		return Mono.just(McpAsyncResponse.streaming(notifier -> listen(ctx, intersect(requested), notifier)));
 	}
 
diff --git a/mcp-core/src/test/java/io/modelcontextprotocol/modern/server/SubscriptionsFeatureTests.java b/mcp-core/src/test/java/io/modelcontextprotocol/modern/server/SubscriptionsFeatureTests.java
index 21cd7786d..5b450bf02 100644
--- a/mcp-core/src/test/java/io/modelcontextprotocol/modern/server/SubscriptionsFeatureTests.java
+++ b/mcp-core/src/test/java/io/modelcontextprotocol/modern/server/SubscriptionsFeatureTests.java
@@ -211,6 +211,41 @@ void resourceSubscribeIsNotAdvertisedWithoutSubscriptions() {
 		assertThat(resourcesCapability(server)).containsEntry("subscribe", false);
 	}
 
+	@Test
+	void listenWithoutNotificationsIsRejectedAsInvalidParams() {
+		McpServer server = toolsServer(new McpChangeFeed());
+		JSONRPCRequest request = new JSONRPCRequest("subscriptions/listen", 1, Map.of("_meta", meta()));
+
+		assertThat(server.handle(McpTransportContext.EMPTY, request).block()).isInstanceOfSatisfying(
+				McpTransportResponse.Error.class,
+				error -> assertThat(error.response().error().code()).isEqualTo(McpSchema.ErrorCodes.INVALID_PARAMS));
+	}
+
+	@Test
+	void listenWithNullNotificationsIsRejectedAsInvalidParams() {
+		McpServer server = toolsServer(new McpChangeFeed());
+		Map<String, Object> params = new HashMap<>();
+		params.put("_meta", meta());
+		params.put("notifications", null);
+		JSONRPCRequest request = new JSONRPCRequest("subscriptions/listen", 1, params);
+
+		assertThat(server.handle(McpTransportContext.EMPTY, request).block()).isInstanceOfSatisfying(
+				McpTransportResponse.Error.class,
+				error -> assertThat(error.response().error().code()).isEqualTo(McpSchema.ErrorCodes.INVALID_PARAMS));
+	}
+
+	@Test
+	void listenWithEmptyNotificationsIsAccepted() {
+		McpServer server = toolsServer(new McpChangeFeed());
+		Map<String, Object> params = new HashMap<>();
+		params.put("_meta", meta());
+		params.put("notifications", Map.of());
+		JSONRPCRequest request = new JSONRPCRequest("subscriptions/listen", 1, params);
+
+		assertThat(server.handle(McpTransportContext.EMPTY, request).block())
+			.isInstanceOf(McpTransportResponse.Streaming.class);
+	}
+
 	private static McpServer resourcesServer(boolean supportsSubscribe, McpChangePublisher publisher) {
 		McpAsyncResourceRepository repository = new McpAsyncResourceRepository() {
 			@Override
diff --git a/mcp-test/src/test/java/io/modelcontextprotocol/modern/server/transport/HttpServletMcpTransportIntegrationTests.java b/mcp-test/src/test/java/io/modelcontextprotocol/modern/server/transport/HttpServletMcpTransportIntegrationTests.java
index 4dc8e6990..620a8d8c3 100644
--- a/mcp-test/src/test/java/io/modelcontextprotocol/modern/server/transport/HttpServletMcpTransportIntegrationTests.java
+++ b/mcp-test/src/test/java/io/modelcontextprotocol/modern/server/transport/HttpServletMcpTransportIntegrationTests.java
@@ -6,6 +6,7 @@
 
 import java.io.BufferedReader;
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.net.Socket;
@@ -260,6 +261,19 @@ void unknownToolIsInvalidParams() throws Exception {
 		assertThat(errorCode(response)).isEqualTo(ErrorCodes.INVALID_PARAMS);
 	}
 
+	@Test
+	void listenWithoutNotificationsIsInvalidParams() throws Exception {
+		HttpRequest request = post("subscriptions/listen", Map.of("_meta", meta())).build();
+		HttpResponse<InputStream> response = HttpClient.newHttpClient()
+			.send(request, HttpResponse.BodyHandlers.ofInputStream());
+
+		try (InputStream body = response.body()) {
+			assertThat(response.statusCode()).isEqualTo(400);
+			assertThat(new String(body.readAllBytes(), StandardCharsets.UTF_8))
+				.contains("\"code\":" + ErrorCodes.INVALID_PARAMS);
+		}
+	}
+
 	@Test
 	void streamingBodyExceptionIsAnsweredInStream() throws Exception {
 		HttpResponse<String> response = callTool("fails-streaming");