diff --git a/src/rbd.cc b/src/rbd.cc
index f43cb03a45f..f490c700dcb 100644
--- a/src/rbd.cc
+++ b/src/rbd.cc
@@ -1344,79 +1344,87 @@ int main(int argc, const char **argv)
     return EXIT_FAILURE;
   }
 
-  for (i = args.erase(i); i != args.end(); ++i) {
-    const char *v = *i;
-    switch (opt_cmd) {
-      case OPT_LIST:
-	set_conf_param(v, &poolname, NULL);
-	break;
-      case OPT_INFO:
-      case OPT_CREATE:
-      case OPT_FLATTEN:
-      case OPT_RESIZE:
-      case OPT_RM:
-      case OPT_SNAP_CREATE:
-      case OPT_SNAP_ROLLBACK:
-      case OPT_SNAP_REMOVE:
-      case OPT_SNAP_LIST:
-      case OPT_SNAP_PURGE:
-      case OPT_SNAP_PROTECT:
-      case OPT_SNAP_UNPROTECT:
-      case OPT_WATCH:
-      case OPT_MAP:
-      case OPT_LOCK_LIST:
+  i = args.erase(i);
+  const char *v = *i;
+  switch (opt_cmd) {
+    case OPT_LIST:
+      set_conf_param(v, &poolname, NULL);
+      break;
+    case OPT_INFO:
+    case OPT_CREATE:
+    case OPT_FLATTEN:
+    case OPT_RESIZE:
+    case OPT_RM:
+    case OPT_SNAP_CREATE:
+    case OPT_SNAP_ROLLBACK:
+    case OPT_SNAP_REMOVE:
+    case OPT_SNAP_LIST:
+    case OPT_SNAP_PURGE:
+    case OPT_SNAP_PROTECT:
+    case OPT_SNAP_UNPROTECT:
+    case OPT_WATCH:
+    case OPT_MAP:
+    case OPT_LOCK_LIST:
+      set_conf_param(v, &imgname, NULL);
+      break;
+    case OPT_UNMAP:
+      set_conf_param(v, &devpath, NULL);
+      break;
+    case OPT_EXPORT:
+      set_conf_param(v, &imgname, &path);
+      break;
+    case OPT_IMPORT:
+      set_conf_param(v, &path, &destname);
+      break;
+    case OPT_COPY:
+    case OPT_RENAME:
+      set_conf_param(v, &imgname, &destname);
+      break;
+    case OPT_CLONE:
+      if (imgname == NULL) {
 	set_conf_param(v, &imgname, NULL);
-	break;
-      case OPT_UNMAP:
-	set_conf_param(v, &devpath, NULL);
-	break;
-      case OPT_EXPORT:
-	set_conf_param(v, &imgname, &path);
-	break;
-      case OPT_IMPORT:
-	set_conf_param(v, &path, &destname);
-	break;
-      case OPT_COPY:
-      case OPT_RENAME:
-	set_conf_param(v, &imgname, &destname);
-	break;
-      case OPT_CLONE:
-	if (imgname == NULL) {
-	  set_conf_param(v, &imgname, NULL);
-        } else {
-	  set_conf_param(v, &destname, NULL);
-	}
-	break;
-      case OPT_SHOWMAPPED:
-	usage();
+      } else {
+	set_conf_param(v, &destname, NULL);
+      }
+      break;
+    case OPT_SHOWMAPPED:
+      usage();
+      return EXIT_FAILURE;
+    case OPT_CHILDREN:
+      set_conf_param(v, &imgname, NULL);
+      break;
+    case OPT_LOCK_ADD:
+      if (args.size() < 2) {
+	cerr << "error: not enough arguments to lock add" << std::endl;
 	return EXIT_FAILURE;
-      case OPT_CHILDREN:
-	set_conf_param(v, &imgname, NULL);
-	break;
-      case OPT_LOCK_ADD:
-	if (args.size() < 2) {
-	  cerr << "error: not enough arguments to lock add" << std::endl;
-	  return EXIT_FAILURE;
-	}
-	set_conf_param(v, &imgname, NULL);
-	v = *(++i);
-	set_conf_param(v, &lock_cookie, NULL);
-	break;
-      case OPT_LOCK_REMOVE:
-	if (args.size() < 3) {
-	  cerr << "error: not enough arguments to lock remove" << std::endl;
-	  return EXIT_FAILURE;
-	}
-	set_conf_param(v, &imgname, NULL);
-	v = *(++i);
-	set_conf_param(v, &lock_client, NULL);
-	v = *(++i);
-	set_conf_param(v, &lock_cookie, NULL);
-	break;
+      }
+      set_conf_param(v, &imgname, NULL);
+      v = *(++i);
+      set_conf_param(v, &lock_cookie, NULL);
+      break;
+    case OPT_LOCK_REMOVE:
+      if (args.size() < 3) {
+	cerr << "error: not enough arguments to lock remove" << std::endl;
+	return EXIT_FAILURE;
+      }
+      set_conf_param(v, &imgname, NULL);
+      v = *(++i);
+      set_conf_param(v, &lock_client, NULL);
+      v = *(++i);
+      set_conf_param(v, &lock_cookie, NULL);
+      break;
     default:
-	assert(0);
-	break;
+      assert(0);
+      break;
+  }
+  if (i != args.end()) {
+    cerr << "rbd: extra arguments given: ";
+    while (i < args.end()) {
+      cerr << *i << " ";
+      i++;
     }
+    cerr << std::endl;
+    return EXIT_FAILURE;
   }
 
   if (format_specified && opt_cmd != OPT_IMPORT && opt_cmd != OPT_CREATE) {