diff --git a/src/hello_imgui/impl/dpi_aware.cpp b/src/hello_imgui/impl/dpi_aware.cpp
index 24d68f71..4b3b246f 100644
--- a/src/hello_imgui/impl/dpi_aware.cpp
+++ b/src/hello_imgui/impl/dpi_aware.cpp
@@ -10,40 +10,41 @@ namespace HelloImGui
 
     float EmSize()
     {
-        IM_ASSERT(GImGui != NULL); // EmSize can only be called after ImGui context was created!
+        IM_ASSERT(GImGui != NULL && "EmSize can only be called after ImGui context was created!");
         float r = ImGui::GetFontSize();
         return r;
     }
 
     float EmSize(float nbLines)
     {
+        IM_ASSERT(GImGui != NULL && "EmSize can only be called after ImGui context was created!");
         return ImGui::GetFontSize() * nbLines;
     }
 
     ImVec2 EmToVec2(float x, float y)
     {
-        IM_ASSERT(GImGui != NULL);
+        IM_ASSERT(GImGui != NULL && "EmToVec2 can only be called after ImGui context was created!");
         float k = ImGui::GetFontSize();
         return ImVec2(k * x, k * y);
     }
 
     ImVec2 EmToVec2(ImVec2 v)
     {
-        IM_ASSERT(GImGui != NULL);
+        IM_ASSERT(GImGui != NULL && "EmToVec2 can only be called after ImGui context was created!");
         float k = ImGui::GetFontSize();
         return ImVec2(k * v.x, k * v.y);
     }
 
     ImVec2 PixelsToEm(ImVec2 pixels)
     {
-        IM_ASSERT(GImGui != NULL);
+        IM_ASSERT(GImGui != NULL && "PixelsToEm can only be called after ImGui context was created!");
         float k = ImGui::GetFontSize();
         return ImVec2(pixels.x / k, pixels.y / k);
     }
 
     float  PixelSizeToEm(float pixelSize)
     {
-        IM_ASSERT(GImGui != NULL);
+        IM_ASSERT(GImGui != NULL && "PixelSizeToEm can only be called after ImGui context was created!");
         float k = ImGui::GetFontSize();
         return pixelSize / k;
     }