diff --git a/cpp/robot-name/robot_name.cpp b/cpp/robot-name/robot_name.cpp
index 5b79010..1a06dcf 100644
--- a/cpp/robot-name/robot_name.cpp
+++ b/cpp/robot-name/robot_name.cpp
@@ -1,6 +1,7 @@
 #include "robot_name.h"
 
 #include <algorithm>
+#include <stdexcept>
 #include <set>
 #include <random>
 
@@ -49,6 +50,9 @@ void robot::reset()
     static distribution_t alpha_distribution('A', 'Z');
     static distribution_t digit_distribution('0', '9');
 
+    if (used_names.size() >= name_capacity)
+        throw length_error("no more names available");
+
     string new_name;
 
     do {
@@ -56,7 +60,7 @@ void robot::reset()
         new_name = random_string(alpha_part_size, alpha_distribution)
                  + random_string(digit_part_size, digit_distribution);
 
-    } while (used_names.size() < name_capacity && used_names.count(new_name));
+    } while (used_names.count(new_name));
 
     used_names.erase(name_);
     name_ = new_name;