diff --git a/src/hydro/Minimal/hydro.h b/src/hydro/Minimal/hydro.h
index da4699d2ebced5650edea8608d6ec97db112090d..b5cceacc31bfaeec0941c855a1c193a9bd36c4a6 100644
--- a/src/hydro/Minimal/hydro.h
+++ b/src/hydro/Minimal/hydro.h
@@ -18,7 +18,7 @@
  ******************************************************************************/
 
 #include "approx_math.h"
-#include "gamma.h"
+#include "adiabatic_index.h"
 
 /**
  * @brief Computes the hydro time-step of a given particle