diff --git a/src/main/kotlin/io/supabase/postgrest/PostgrestDefaultClient.kt b/src/main/kotlin/io/supabase/postgrest/PostgrestDefaultClient.kt
index 7e3e088..8397c35 100644
--- a/src/main/kotlin/io/supabase/postgrest/PostgrestDefaultClient.kt
+++ b/src/main/kotlin/io/supabase/postgrest/PostgrestDefaultClient.kt
@@ -27,7 +27,7 @@ class PostgrestDefaultClient(
         headers = headers,
         schema = schema,
         httpClient = PostgrestHttpClientApache(
-                postgrestJsonConverter = jsonConverter,
+                jsonConverter = jsonConverter,
                 httpClient = { HttpClients.createDefault() }
         ),
         jsonConverter = jsonConverter
diff --git a/src/main/kotlin/io/supabase/postgrest/builder/PostgrestQueryBuilder.kt b/src/main/kotlin/io/supabase/postgrest/builder/PostgrestQueryBuilder.kt
index 4cd7737..4228773 100644
--- a/src/main/kotlin/io/supabase/postgrest/builder/PostgrestQueryBuilder.kt
+++ b/src/main/kotlin/io/supabase/postgrest/builder/PostgrestQueryBuilder.kt
@@ -48,7 +48,7 @@ class PostgrestQueryBuilder<T : Any>(url: URI, postgrestHttpClient: PostgrestHtt
     fun insert(values: List<T>, upsert: Boolean = false, onConflict: String? = null, returning: Returning = Returning.REPRESENTATION, count: Count? = null): PostgrestFilterBuilder<T> {
         setMethod(Method.POST)
 
-        val preferHeaders = mutableListOf<String>("return=${returning.identifier}")
+        val preferHeaders = mutableListOf("return=${returning.identifier}")
         if (upsert) preferHeaders.add("resolution=merge-duplicates")
 
         if (upsert && onConflict != null) setSearchParam("on_conflict", onConflict)
diff --git a/src/main/kotlin/io/supabase/postgrest/http/PostgrestHttpClientApache.kt b/src/main/kotlin/io/supabase/postgrest/http/PostgrestHttpClientApache.kt
index 52acc0c..46ff0a1 100644
--- a/src/main/kotlin/io/supabase/postgrest/http/PostgrestHttpClientApache.kt
+++ b/src/main/kotlin/io/supabase/postgrest/http/PostgrestHttpClientApache.kt
@@ -3,7 +3,6 @@ package io.supabase.postgrest.http
 import io.supabase.postgrest.json.PostgrestJsonConverter
 import org.apache.hc.client5.http.classic.methods.HttpUriRequestBase
 import org.apache.hc.client5.http.impl.classic.CloseableHttpClient
-import org.apache.hc.client5.http.impl.classic.HttpClients
 import org.apache.hc.core5.http.ClassicHttpResponse
 import org.apache.hc.core5.http.HttpStatus
 import org.apache.hc.core5.http.Method
@@ -19,14 +18,14 @@ import java.net.URI
  */
 class PostgrestHttpClientApache(
         private val httpClient: () -> CloseableHttpClient,
-        private val postgrestJsonConverter: PostgrestJsonConverter
+        private val jsonConverter: PostgrestJsonConverter
 ) : PostgrestHttpClient {
 
     override fun execute(uri: URI, method: Method, headers: Map<String, String>, body: Any?): PostgrestHttpResponse {
         return httpClient().use { httpClient ->
             val httpRequest = HttpUriRequestBase(method.name, uri)
             body?.apply {
-                val dataAsString = postgrestJsonConverter.serialize(body)
+                val dataAsString = jsonConverter.serialize(body)
                 httpRequest.entity = StringEntity(dataAsString)
             }
             headers.forEach { (name, value) -> httpRequest.addHeader(name, value) }
diff --git a/src/test/kotlin/io/supabase/postgrest/http/PostgrestHttpClientApacheTest.kt b/src/test/kotlin/io/supabase/postgrest/http/PostgrestHttpClientApacheTest.kt
new file mode 100644
index 0000000..9e0e442
--- /dev/null
+++ b/src/test/kotlin/io/supabase/postgrest/http/PostgrestHttpClientApacheTest.kt
@@ -0,0 +1,118 @@
+package io.supabase.postgrest.http
+
+import assertk.assertAll
+import assertk.assertThat
+import assertk.assertions.hasSize
+import assertk.assertions.isEqualTo
+import io.mockk.CapturingSlot
+import io.mockk.every
+import io.mockk.mockk
+import io.mockk.slot
+import io.supabase.postgrest.json.PostgrestJsonConverterJackson
+import org.apache.hc.client5.http.impl.classic.CloseableHttpClient
+import org.apache.hc.client5.http.impl.classic.CloseableHttpResponse
+import org.apache.hc.core5.http.ClassicHttpRequest
+import org.apache.hc.core5.http.Method
+import org.apache.hc.core5.http.io.HttpClientResponseHandler
+import org.apache.hc.core5.http.io.entity.StringEntity
+import org.junit.jupiter.api.Nested
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.api.TestInstance
+import org.junit.jupiter.api.assertThrows
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.MethodSource
+import java.net.URI
+import java.util.stream.Stream
+
+internal class PostgrestHttpClientApacheTest {
+
+    private val uri = "https://test.com"
+    private val httpClientMock = mockk<CloseableHttpClient>()
+
+    private val postgrestHttpClient = PostgrestHttpClientApache(
+            httpClient = { httpClientMock },
+            jsonConverter = PostgrestJsonConverterJackson()
+    )
+
+    init {
+        every { httpClientMock.close() }.returns(Unit)
+    }
+
+    @Test
+    fun `should set http headers`() {
+        val httpResponse = mockk<CloseableHttpResponse>()
+        every { httpResponse.code } returns 200
+        every { httpResponse.entity } returns null
+
+        val requestCapture = mockHttpCallWithGetRequest(httpResponse)
+
+        val headers = mapOf("Authorization" to "foobar", "Content-Type" to "application/json")
+
+        postgrestHttpClient.execute(
+                method = Method.GET,
+                uri = URI(uri),
+                headers = headers
+        )
+
+        val request = requestCapture.captured
+
+        assertAll {
+            assertThat(request.headers).hasSize(headers.size)
+            headers.forEach { (name, value) ->
+                assertThat(request.getHeader(name).value).isEqualTo(value)
+            }
+        }
+    }
+
+    @Nested
+    @TestInstance(TestInstance.Lifecycle.PER_CLASS)
+    inner class ThrowHttpException {
+
+        @ParameterizedTest
+        @MethodSource("exceptionTestData")
+        fun `should throw http exception when status is above 300`(testData: ExceptionTestData) {
+            val httpResponse = mockk<CloseableHttpResponse>()
+            val responseCode = testData.status
+            val httpBody = testData.body
+
+            every { httpResponse.code } returns responseCode
+            every { httpResponse.entity } returns httpBody?.let { StringEntity(it) }
+
+            mockHttpCallWithGetRequest(httpResponse)
+
+            val exception = assertThrows<PostgrestHttpException> {
+                postgrestHttpClient.execute(
+                        method = Method.GET,
+                        uri = URI(uri)
+                )
+            }
+
+            assertThat(exception.status).isEqualTo(responseCode)
+            assertThat(exception.data).isEqualTo(httpBody)
+        }
+
+        @Suppress("unused")
+        private fun exceptionTestData(): Stream<ExceptionTestData> {
+            return Stream.of(
+                    ExceptionTestData(301, "httpbody"),
+                    ExceptionTestData(301, null),
+                    ExceptionTestData(400, "httpbody")
+            )
+        }
+    }
+
+    data class ExceptionTestData(
+            val status: Int,
+            val body: String?
+    )
+
+    private fun mockHttpCallWithGetRequest(httpResponse: CloseableHttpResponse): CapturingSlot<ClassicHttpRequest> {
+        val slot = slot<ClassicHttpRequest>()
+        every { httpClientMock.execute(capture(slot), any<HttpClientResponseHandler<Any>>()) }.answers {
+            val handler = args[1] as HttpClientResponseHandler<*>
+            handler.handleResponse(httpResponse)
+        }
+
+        return slot
+    }
+}
\ No newline at end of file