diff --git a/Outputs/CRT/Internals/CRTOpenGL.cpp b/Outputs/CRT/Internals/CRTOpenGL.cpp
index 261e10bc1..077adf612 100644
--- a/Outputs/CRT/Internals/CRTOpenGL.cpp
+++ b/Outputs/CRT/Internals/CRTOpenGL.cpp
@@ -7,8 +7,9 @@
 
 #include "../CRT.hpp"
 
-#include <cstdlib>
+#include <cassert>
 #include <cmath>
+#include <cstdlib>
 
 #include "CRTOpenGL.hpp"
 #include "../../../SignalProcessing/FIRFilter.hpp"