diff --git a/src/main/java/org/asamk/signal/commands/GetAttachmentCommand.java b/src/main/java/org/asamk/signal/commands/GetAttachmentCommand.java
index cf716194..c640ee83 100644
--- a/src/main/java/org/asamk/signal/commands/GetAttachmentCommand.java
+++ b/src/main/java/org/asamk/signal/commands/GetAttachmentCommand.java
@@ -41,6 +41,9 @@ public class GetAttachmentCommand implements JsonRpcLocalCommand {
     ) throws CommandException {
 
         final var id = ns.getString("id");
+        if (id == null) {
+            throw new UserErrorException("Missing attachment id parameter");
+        }
 
         try (InputStream attachment = m.retrieveAttachment(id)) {
             final var bytes = attachment.readAllBytes();