diff --git a/src/heightmap.cpp b/src/heightmap.cpp
--- a/src/heightmap.cpp
+++ b/src/heightmap.cpp
@@ -22,6 +22,8 @@
 
 #include "table/strings.h"
 
+#include "safeguards.h"
+
 /**
  * Convert RGB colours to Grayscale using 29.9% Red, 58.7% Green, 11.4% Blue
  *  (average luminosity formula, NTSC Colour Space)