diff --git a/src/main/java/io/github/nstdio/http/ext/ExtendedHttpClient.java b/src/main/java/io/github/nstdio/http/ext/ExtendedHttpClient.java
index 587e303..b22033a 100644
--- a/src/main/java/io/github/nstdio/http/ext/ExtendedHttpClient.java
+++ b/src/main/java/io/github/nstdio/http/ext/ExtendedHttpClient.java
@@ -22,6 +22,7 @@
 import java.net.Authenticator;
 import java.net.CookieHandler;
 import java.net.ProxySelector;
+import java.net.URI;
 import java.net.http.HttpClient;
 import java.net.http.HttpRequest;
 import java.net.http.HttpRequest.BodyPublishers;
@@ -162,8 +163,8 @@ public <T> CompletableFuture<HttpResponse<T>> sendAsync(HttpRequest request, Bod
   }
 
   private <T> CompletableFuture<HttpResponse<T>> send0(HttpRequest request, BodyHandler<T> bodyHandler, Sender<T> sender) {
-    if (!allowInsecure && "http".equalsIgnoreCase(request.uri().getScheme())) {
-      throw new IllegalArgumentException("Client does not allow insecure HTTP requests.");
+    if (!allowInsecure) {
+      checkInsecureScheme(request);
     }
 
     Chain<T> chain = buildAndExecute(RequestContext.of(request, bodyHandler));
@@ -176,6 +177,13 @@ private <T> CompletableFuture<HttpResponse<T>> send0(HttpRequest request, BodyHa
     return future.isDone() ? future.handle(handler) : future.handleAsync(handler);
   }
 
+  private void checkInsecureScheme(HttpRequest request) {
+    URI uri = request.uri();
+    if ("http".equalsIgnoreCase(uri.getScheme())) {
+      throw new IllegalArgumentException("Client does not allow insecure HTTP requests. URI: " + uri);
+    }
+  }
+
   private <T> Chain<T> buildAndExecute(RequestContext ctx) {
     Chain<T> chain = Chain.of(ctx);
     chain = compressionInterceptor != null ? compressionInterceptor.intercept(chain) : chain;
diff --git a/src/test/kotlin/io/github/nstdio/http/ext/ExtendedHttpClientTest.kt b/src/test/kotlin/io/github/nstdio/http/ext/ExtendedHttpClientTest.kt
index bca979d..b64bd2b 100644
--- a/src/test/kotlin/io/github/nstdio/http/ext/ExtendedHttpClientTest.kt
+++ b/src/test/kotlin/io/github/nstdio/http/ext/ExtendedHttpClientTest.kt
@@ -17,6 +17,8 @@ package io.github.nstdio.http.ext
 
 import io.github.nstdio.http.ext.ExtendedHttpClient.Builder
 import io.kotest.assertions.throwables.shouldThrowExactly
+import io.kotest.matchers.should
+import io.kotest.matchers.string.shouldEndWith
 import io.kotest.matchers.throwable.shouldHaveCause
 import io.kotest.matchers.types.shouldBeSameInstanceAs
 import org.assertj.core.api.Assertions.assertThatExceptionOfType
@@ -117,15 +119,18 @@ internal class ExtendedHttpClientTest {
     val mockBuilderDelegate = mock(HttpClient.Builder::class.java)
     given(mockBuilderDelegate.build()).willReturn(mockDelegate)
 
+    val uri = "HTTP://abc.local"
     client = Builder(mockBuilderDelegate)
       .allowInsecure(false)
       .build()
 
-    val request = HttpRequest.newBuilder("HTTP://abc.local".toUri()).build()
+    val request = HttpRequest.newBuilder(uri.toUri()).build()
 
     //when + then
     shouldThrowExactly<IllegalArgumentException> {
       client.send(request, ofString())
+    }.should {
+      it.message.shouldEndWith("URI: $uri")
     }
   }