diff --git a/lapis2/src/main/kotlin/org/genspectrum/lapis/silo/SiloClient.kt b/lapis2/src/main/kotlin/org/genspectrum/lapis/silo/SiloClient.kt
index 1366baaa..070aab85 100644
--- a/lapis2/src/main/kotlin/org/genspectrum/lapis/silo/SiloClient.kt
+++ b/lapis2/src/main/kotlin/org/genspectrum/lapis/silo/SiloClient.kt
@@ -3,6 +3,8 @@ package org.genspectrum.lapis.silo
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.module.kotlin.readValue
 import mu.KotlinLogging
+import org.genspectrum.lapis.logging.RequestIdContext
+import org.genspectrum.lapis.openApi.REQUEST_ID_HEADER
 import org.genspectrum.lapis.response.InfoData
 import org.springframework.beans.factory.annotation.Value
 import org.springframework.http.HttpHeaders
@@ -24,19 +26,19 @@ class SiloClient(
     @Value("\${silo.url}") private val siloUrl: String,
     private val objectMapper: ObjectMapper,
     private val dataVersion: DataVersion,
+    private val requestIdContext: RequestIdContext,
 ) {
+    private val httpClient = HttpClient.newHttpClient()
+
     fun <ResponseType> sendQuery(query: SiloQuery<ResponseType>): ResponseType {
         val queryJson = objectMapper.writeValueAsString(query)
 
         log.info { "Calling SILO: $queryJson" }
 
-        val client = HttpClient.newHttpClient()
-        val request = HttpRequest.newBuilder(URI("$siloUrl/query"))
-            .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
-            .POST(HttpRequest.BodyPublishers.ofString(queryJson))
-            .build()
-
-        val response = send(client, request)
+        val response = send(URI("$siloUrl/query")) {
+            it.header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
+                .POST(HttpRequest.BodyPublishers.ofString(queryJson))
+        }
 
         try {
             return objectMapper.readValue(response.body(), query.action.typeReference).queryResult
@@ -49,20 +51,26 @@ class SiloClient(
     fun callInfo(): InfoData {
         log.info { "Calling SILO info" }
 
-        val client = HttpClient.newHttpClient()
-        val request = HttpRequest.newBuilder(URI("$siloUrl/info")).GET().build()
-
-        val response = send(client, request)
+        val response = send(URI("$siloUrl/info")) { it.GET() }
 
         return InfoData(getDataVersion(response))
     }
 
     private fun send(
-        client: HttpClient,
-        request: HttpRequest?,
+        uri: URI,
+        buildRequest: (HttpRequest.Builder) -> Unit,
     ): HttpResponse<String> {
+        val request = HttpRequest.newBuilder(uri)
+            .apply(buildRequest)
+            .apply {
+                if (requestIdContext.requestId != null) {
+                    header(REQUEST_ID_HEADER, requestIdContext.requestId)
+                }
+            }
+            .build()
+
         val response = try {
-            client.send(request, BodyHandlers.ofString())
+            httpClient.send(request, BodyHandlers.ofString())
         } catch (exception: Exception) {
             val message = "Could not connect to silo: " + exception::class.toString() + " " + exception.message
             throw RuntimeException(message, exception)
diff --git a/lapis2/src/test/kotlin/org/genspectrum/lapis/silo/SiloClientTest.kt b/lapis2/src/test/kotlin/org/genspectrum/lapis/silo/SiloClientTest.kt
index 91d3c04c..995aaf3f 100644
--- a/lapis2/src/test/kotlin/org/genspectrum/lapis/silo/SiloClientTest.kt
+++ b/lapis2/src/test/kotlin/org/genspectrum/lapis/silo/SiloClientTest.kt
@@ -3,6 +3,7 @@ package org.genspectrum.lapis.silo
 import com.fasterxml.jackson.databind.node.DoubleNode
 import com.fasterxml.jackson.databind.node.IntNode
 import com.fasterxml.jackson.databind.node.TextNode
+import org.genspectrum.lapis.logging.RequestIdContext
 import org.genspectrum.lapis.response.AggregationData
 import org.genspectrum.lapis.response.DetailsData
 import org.genspectrum.lapis.response.MutationData
@@ -29,18 +30,21 @@ import org.springframework.boot.test.context.SpringBootTest
 
 private const val MOCK_SERVER_PORT = 1080
 
+private const val REQUEST_ID_VALUE = "someRequestId"
+
 @SpringBootTest(properties = ["silo.url=http://localhost:$MOCK_SERVER_PORT"])
-class SiloClientTest {
+class SiloClientTest(
+    @Autowired private val underTest: SiloClient,
+    @Autowired private val requestIdContext: RequestIdContext,
+) {
     private lateinit var mockServer: ClientAndServer
 
-    @Autowired
-    private lateinit var underTest: SiloClient
-
     private val someQuery = SiloQuery(SiloAction.aggregated(), StringEquals("theColumn", "theValue"))
 
     @BeforeEach
     fun setupMockServer() {
         mockServer = ClientAndServer.startClientAndServer(MOCK_SERVER_PORT)
+        requestIdContext.requestId = REQUEST_ID_VALUE
     }
 
     @AfterEach
@@ -337,7 +341,8 @@ class SiloClientTest {
                 request()
                     .withMethod("POST")
                     .withPath("/query")
-                    .withContentType(MediaType.APPLICATION_JSON),
+                    .withContentType(MediaType.APPLICATION_JSON)
+                    .withHeader("X-Request-Id", REQUEST_ID_VALUE),
             )
             .respond(httpResponse)
     }