diff --git a/include/igl/opengl/glfw/imgui/ImGuiHelpers.h b/include/igl/opengl/glfw/imgui/ImGuiHelpers.h
index f35f097..8dcb3af 100644
--- a/include/igl/opengl/glfw/imgui/ImGuiHelpers.h
+++ b/include/igl/opengl/glfw/imgui/ImGuiHelpers.h
@@ -25,28 +25,25 @@
 namespace ImGui
 {

-static auto vector_getter = [](void* vec, int idx, const char** out_text)
+static auto vector_getter = [](void* vec, int idx) -> const char*
 {
   auto& vector = *static_cast<std::vector<std::string>*>(vec);
-  if (idx < 0 || idx >= static_cast<int>(vector.size())) { return false; }
-  *out_text = vector.at(idx).c_str();
-  return true;
+  if (idx < 0 || idx >= static_cast<int>(vector.size())) { return nullptr; }
+  return vector.at(idx).c_str();
 };

 inline bool Combo(const char* label, int* idx, std::vector<std::string>& values)
 {
   if (values.empty()) { return false; }
   return Combo(label, idx, vector_getter,
-    static_cast<void*>(&values), values.size());
+    static_cast<void*>(&values), static_cast<int>(values.size()));
 }

 inline bool Combo(const char* label, int* idx, std::function<const char *(int)> getter, int items_count)
 {
-  auto func = [](void* data, int i, const char** out_text) {
+  auto func = [](void* data, int i) -> const char* {
     auto &getter = *reinterpret_cast<std::function<const char *(int)> *>(data);
-    const char *s = getter(i);
-    if (s) { *out_text = s; return true; }
-    else { return false; }
+    return getter(i);
   };
   return Combo(label, idx, func, reinterpret_cast<void *>(&getter), items_count);
 }
@@ -55,7 +52,7 @@ inline bool ListBox(const char* label, int* idx, std::vector<std::string>& value
 {
   if (values.empty()) { return false; }
   return ListBox(label, idx, vector_getter,
-    static_cast<void*>(&values), values.size());
+    static_cast<void*>(&values), static_cast<int>(values.size()));
 }

 inline bool InputText(const char* label, std::string &str, ImGuiInputTextFlags flags = 0, ImGuiInputTextCallback callback = NULL, void* user_data = NULL)