diff --git a/com.io7m.hibiscus.api/src/main/java/com/io7m/hibiscus/api/HBClientAsynchronousFactoryType.java b/com.io7m.hibiscus.api/src/main/java/com/io7m/hibiscus/api/HBClientAsynchronousFactoryType.java
index b1f6404..7a60b0d 100644
--- a/com.io7m.hibiscus.api/src/main/java/com/io7m/hibiscus/api/HBClientAsynchronousFactoryType.java
+++ b/com.io7m.hibiscus.api/src/main/java/com/io7m/hibiscus/api/HBClientAsynchronousFactoryType.java
@@ -47,7 +47,10 @@ public interface HBClientAsynchronousFactoryType<
    * @param configuration The client configuration
    *
    * @return A new client
+   *
+   * @throws X If a client cannot be created
    */
 
-  L openAsynchronousClient(G configuration);
+  L openAsynchronousClient(G configuration)
+    throws X;
 }
diff --git a/com.io7m.hibiscus.api/src/main/java/com/io7m/hibiscus/api/HBClientSynchronousFactoryType.java b/com.io7m.hibiscus.api/src/main/java/com/io7m/hibiscus/api/HBClientSynchronousFactoryType.java
index 5a76070..0b40a46 100644
--- a/com.io7m.hibiscus.api/src/main/java/com/io7m/hibiscus/api/HBClientSynchronousFactoryType.java
+++ b/com.io7m.hibiscus.api/src/main/java/com/io7m/hibiscus/api/HBClientSynchronousFactoryType.java
@@ -46,8 +46,11 @@ public interface HBClientSynchronousFactoryType<
    *
    * @param configuration The client configuration
    *
+   * @throws X If a client cannot be created
+   *
    * @return A new client
    */
 
-  L openSynchronousClient(G configuration);
+  L openSynchronousClient(G configuration)
+    throws X;
 }