diff --git a/src/main/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequestAssertions.java b/src/main/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequestAssertions.java
index 0ccf3c9..5dc54fe 100644
--- a/src/main/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequestAssertions.java
+++ b/src/main/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequestAssertions.java
@@ -30,7 +30,7 @@ public class RecordedRequestAssertions {
     private final RecordedRequest recordedRequest;
 
     private RecordedRequestAssertions(RecordedRequest recordedRequest) {
-        this.recordedRequest = requireNotNull(recordedRequest);
+        this.recordedRequest = requireNotNull(recordedRequest, "recordedRequest must not be null");
     }
 
     /**
diff --git a/src/main/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequests.java b/src/main/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequests.java
index b9136ae..8c749ff 100644
--- a/src/main/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequests.java
+++ b/src/main/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequests.java
@@ -12,7 +12,7 @@
 import java.util.concurrent.TimeUnit;
 
 /**
- * Contains test assertions for {@link RecordedRequest} when using {@link MockWebServer}.
+ * Contains utilities for working with {@link RecordedRequest} when using {@link MockWebServer}.
  */
 @UtilityClass
 @Slf4j
diff --git a/src/test/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequestAssertionsTest.java b/src/test/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequestAssertionsTest.java
index ae2ade7..90c0dc0 100644
--- a/src/test/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequestAssertionsTest.java
+++ b/src/test/java/org/kiwiproject/test/okhttp3/mockwebserver/RecordedRequestAssertionsTest.java
@@ -2,6 +2,7 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatCode;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.junit.jupiter.api.Assertions.assertAll;
 import static org.kiwiproject.base.KiwiStrings.f;
@@ -52,6 +53,19 @@ void setUp() {
                 .build();
     }
 
+    @Test
+    void shouldRequireNonNullRecordedRequest() {
+        assertAll(
+                () -> assertThatIllegalArgumentException()
+                        .isThrownBy(() -> RecordedRequestAssertions.assertThat(null).isGET())
+                        .withMessage("recordedRequest must not be null"),
+
+                () -> assertThatIllegalArgumentException()
+                        .isThrownBy(() -> RecordedRequestAssertions.assertThatRecordedRequest(null).isPOST())
+                        .withMessage("recordedRequest must not be null")
+        );
+    }
+
     @Test
     void shouldCreateUsingAssertThat() {
         server.enqueue(new MockResponse());