1 files changed, 8 insertions, 1 deletions
diff --git a/routing/joint_index.hpp b/routing/joint_index.hpp
index 0bc95a6b3b..0e3c8c0441 100644
--- a/routing/joint_index.hpp
+++ b/routing/joint_index.hpp
@@ -4,6 +4,8 @@
 #include "routing/road_index.hpp"
 #include "routing/road_point.hpp"
 
+#include "base/assert.hpp"
+
 #include "std/vector.hpp"
 
 namespace routing
@@ -16,7 +18,12 @@ class JointIndex final
 {
 public:
   // Read comments in Build method about -1.
-  uint32_t GetNumJoints() const { return m_offsets.size() - 1; }
+  uint32_t GetNumJoints() const
+  {
+    CHECK_GREATER(m_offsets.size(), 0, ());
+    return m_offsets.size() - 1;
+  }
+
   uint32_t GetNumPoints() const { return m_points.size(); }
   RoadPoint GetPoint(Joint::Id jointId) const { return m_points[Begin(jointId)]; }