diff --git a/src/cooling/const_du/cooling.h b/src/cooling/const_du/cooling.h
index 69424fa331b60964fd7448b08ecc59d7751a492d..92efcafa4ee25006d0651d9f97db82e85c88b3a1 100644
--- a/src/cooling/const_du/cooling.h
+++ b/src/cooling/const_du/cooling.h
@@ -41,6 +41,7 @@
 #include <math.h>
 
 /* Local includes. */
+#include "cosmology.h"
 #include "entropy_floor.h"
 #include "hydro.h"
 #include "parser.h"
diff --git a/src/cooling/const_du/cooling_io.h b/src/cooling/const_du/cooling_io.h
index 0ecb2ebe517f322f32ee4701d63d2153cfd2900d..4fd7bc06a5cbd79f84a9fb04ac894b8a59ff806a 100644
--- a/src/cooling/const_du/cooling_io.h
+++ b/src/cooling/const_du/cooling_io.h
@@ -35,6 +35,7 @@
 
 /* Local includes */
 #include "cooling.h"
+#include "engine.h"
 #include "io_properties.h"
 
 #ifdef HAVE_HDF5
diff --git a/src/cooling/const_lambda/cooling.h b/src/cooling/const_lambda/cooling.h
index 1597687bf6feec49f88f8a2f2b4bba05ecbf5939..b8f28f5999d303d8970293026ade508ed9d0d597 100644
--- a/src/cooling/const_lambda/cooling.h
+++ b/src/cooling/const_lambda/cooling.h
@@ -37,6 +37,7 @@
 
 /* Local includes. */
 #include "const.h"
+#include "cosmology.h"
 #include "entropy_floor.h"
 #include "error.h"
 #include "hydro.h"
diff --git a/src/cooling/const_lambda/cooling_io.h b/src/cooling/const_lambda/cooling_io.h
index 091d567066a9f490050d77ce27f96d4140ecb39d..d68543ae6caeb59b348a16d3b5d8e206849cd1b7 100644
--- a/src/cooling/const_lambda/cooling_io.h
+++ b/src/cooling/const_lambda/cooling_io.h
@@ -33,6 +33,7 @@
 
 /* Local includes */
 #include "cooling.h"
+#include "engine.h"
 #include "io_properties.h"
 
 #ifdef HAVE_HDF5