diff --git a/ray_tracing__advance/hello_vulkan.cpp b/ray_tracing__advance/hello_vulkan.cpp
index 55c0dff..c796103 100644
--- a/ray_tracing__advance/hello_vulkan.cpp
+++ b/ray_tracing__advance/hello_vulkan.cpp
@@ -418,8 +418,8 @@ void HelloVulkan::rasterize(const VkCommandBuffer& cmdBuf)
   vkCmdBindPipeline(cmdBuf, VK_PIPELINE_BIND_POINT_GRAPHICS, m_graphicsPipeline);
   vkCmdBindDescriptorSets(cmdBuf, VK_PIPELINE_BIND_POINT_GRAPHICS, m_pipelineLayout, 0, 1, &m_descSet, 0, nullptr);
 
-
-  for(int i = 0; i < m_objInstance.size(); ++i)
+  uint32_t nbInst = static_cast<uint32_t>(m_objInstance.size() - 1);  // Remove the implicit object
+  for(uint32_t i = 0; i < nbInst; ++i)
   {
     auto& inst                 = m_objInstance[i];
     auto& model                = m_objModel[inst.objIndex];
diff --git a/ray_tracing__advance/main.cpp b/ray_tracing__advance/main.cpp
index ef2d7e0..52719b9 100644
--- a/ray_tracing__advance/main.cpp
+++ b/ray_tracing__advance/main.cpp
@@ -200,7 +200,7 @@ int main(int argc, char** argv)
 
   for(int n = 0; n < 50; ++n)
   {
-    ObjInstance inst;
+    ObjInstance inst    = helloVk.m_objInstance[wusonIndex];
     inst.objIndex       = wusonIndex;
     inst.txtOffset      = 0;
     float         scale = fabsf(disn(gen));
diff --git a/ray_tracing_intersection/hello_vulkan.cpp b/ray_tracing_intersection/hello_vulkan.cpp
index a9e5b1e..813fdc9 100644
--- a/ray_tracing_intersection/hello_vulkan.cpp
+++ b/ray_tracing_intersection/hello_vulkan.cpp
@@ -427,7 +427,8 @@ void HelloVulkan::rasterize(const VkCommandBuffer& cmdBuf)
   vkCmdBindDescriptorSets(cmdBuf, VK_PIPELINE_BIND_POINT_GRAPHICS, m_pipelineLayout, 0, 1, &m_descSet, 0, nullptr);
 
 
-  for(int i = 0; i < m_objInstance.size(); ++i)
+  uint32_t nbInst = static_cast<uint32_t>(m_objInstance.size() - 1);  // Remove the implicit object
+  for(uint32_t i = 0; i < nbInst; ++i)
   {
     auto& inst                = m_objInstance[i];
     auto& model               = m_objModel[inst.objIndex];