diff --git a/openai-java-core/src/main/kotlin/com/openai/core/http/RetryingHttpClient.kt b/openai-java-core/src/main/kotlin/com/openai/core/http/RetryingHttpClient.kt
index 317205674..1a431c653 100644
--- a/openai-java-core/src/main/kotlin/com/openai/core/http/RetryingHttpClient.kt
+++ b/openai-java-core/src/main/kotlin/com/openai/core/http/RetryingHttpClient.kt
@@ -131,7 +131,18 @@ private constructor(
     }
 
     override fun close() {
-        httpClient.close()
+        try {
+            httpClient.close()
+        } catch (httpClientFailure: Throwable) {
+            try {
+                sleeper.close()
+            } catch (sleeperFailure: Throwable) {
+                if (sleeperFailure !== httpClientFailure) {
+                    httpClientFailure.addSuppressed(sleeperFailure)
+                }
+            }
+            throw httpClientFailure
+        }
         sleeper.close()
     }
 
diff --git a/openai-java-core/src/test/kotlin/com/openai/core/http/RetryingHttpClientCloseTest.kt b/openai-java-core/src/test/kotlin/com/openai/core/http/RetryingHttpClientCloseTest.kt
new file mode 100644
index 000000000..24ca07f3b
--- /dev/null
+++ b/openai-java-core/src/test/kotlin/com/openai/core/http/RetryingHttpClientCloseTest.kt
@@ -0,0 +1,73 @@
+package com.openai.core.http
+
+import com.openai.core.Sleeper
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+import org.mockito.kotlin.doThrow
+import org.mockito.kotlin.mock
+import org.mockito.kotlin.verify
+import org.mockito.kotlin.whenever
+
+internal class RetryingHttpClientCloseTest {
+
+    @Test
+    fun closeClosesDelegateAndSleeper() {
+        val delegate = mock<HttpClient>()
+        val sleeper = mock<Sleeper>()
+        val client = client(delegate, sleeper)
+
+        client.close()
+
+        verify(delegate).close()
+        verify(sleeper).close()
+    }
+
+    @Test
+    fun closeStillClosesSleeperWhenDelegateCloseFails() {
+        val delegateFailure = IllegalStateException("delegate close failed")
+        val delegate = mock<HttpClient>()
+        val sleeper = mock<Sleeper>()
+        doThrow(delegateFailure).whenever(delegate).close()
+        val client = client(delegate, sleeper)
+
+        val thrown = runCatching { client.close() }.exceptionOrNull()
+
+        assertThat(thrown).isSameAs(delegateFailure)
+        verify(sleeper).close()
+    }
+
+    @Test
+    fun closeSuppressesSleeperFailureWhenBothCloseOperationsFail() {
+        val delegateFailure = IllegalStateException("delegate close failed")
+        val sleeperFailure = IllegalArgumentException("sleeper close failed")
+        val delegate = mock<HttpClient>()
+        val sleeper = mock<Sleeper>()
+        doThrow(delegateFailure).whenever(delegate).close()
+        doThrow(sleeperFailure).whenever(sleeper).close()
+        val client = client(delegate, sleeper)
+
+        val thrown = runCatching { client.close() }.exceptionOrNull()
+
+        assertThat(thrown).isSameAs(delegateFailure)
+        assertThat(thrown!!.suppressed).containsExactly(sleeperFailure)
+        verify(sleeper).close()
+    }
+
+    @Test
+    fun closePropagatesSleeperFailureWhenDelegateClosesSuccessfully() {
+        val sleeperFailure = IllegalStateException("sleeper close failed")
+        val delegate = mock<HttpClient>()
+        val sleeper = mock<Sleeper>()
+        doThrow(sleeperFailure).whenever(sleeper).close()
+        val client = client(delegate, sleeper)
+
+        val thrown = runCatching { client.close() }.exceptionOrNull()
+
+        assertThat(thrown).isSameAs(sleeperFailure)
+        verify(delegate).close()
+        verify(sleeper).close()
+    }
+
+    private fun client(delegate: HttpClient, sleeper: Sleeper): HttpClient =
+        RetryingHttpClient.builder().httpClient(delegate).sleeper(sleeper).build()
+}