diff --git a/src/equation_of_state/isothermal/equation_of_state.h b/src/equation_of_state/isothermal/equation_of_state.h
index c798c08b0da07a954d21d3c6f6b40d188194fea6..c7afac6caaacf354f8067218fbe2013b9287309a 100644
--- a/src/equation_of_state/isothermal/equation_of_state.h
+++ b/src/equation_of_state/isothermal/equation_of_state.h
@@ -29,8 +29,10 @@
 #include "physical_constants.h"
 
 extern struct eos_parameters eos;
-/* ------------------------------------------------------------------------- */
 
+/**
+ * @brief The parameters of the equation of state for the gas.
+ */
 struct eos_parameters {
 
   /*! Thermal energy per unit mass */