diff --git a/src/physical_constants.c b/src/physical_constants.c
index 0b75b7ceb37ed41a1506e8004782d9ac431e86a2..8f549e60dfcd82d03227ea94ff9e764723d56808 100644
--- a/src/physical_constants.c
+++ b/src/physical_constants.c
@@ -18,13 +18,25 @@
  *
  ******************************************************************************/
 
-#include "physical_constants_cgs.h"
+/* Config parameters. */
+#include "../config.h"
 
+/* This object's header. */
 #include "physical_constants.h"
 
+/* Local headers. */
+#include "physical_constants_cgs.h"
+
+/**
+ * @brief Converts physical constants to the internal unit system
+ *
+ * @param us The current internal system of units.
+ * @param internal_const The physical constants to initialize.
+ */
 void initPhysicalConstants(struct UnitSystem* us,
-                           struct phys_const* prog_const) {
-  float dimension[5] = {1, -3, 2, 0, 0};
-  prog_const->newton_gravity =
+                           struct phys_const* internal_const) {
+
+  const float dimension[5] = {1, -3, 2, 0, 0};
+  internal_const->newton_gravity =
       NEWTON_GRAVITY_CGS * generalConversionFactor(us, dimension);
 }
diff --git a/src/physical_constants.h b/src/physical_constants.h
index 1c5f333485e0b19f58eaeb0a78c85fed156a065f..7c68f20f4a08444fab6a792f887334d152cd1caf 100644
--- a/src/physical_constants.h
+++ b/src/physical_constants.h
@@ -20,6 +20,10 @@
 #ifndef SWIFT_PHYSICAL_CONSTANTS_H
 #define SWIFT_PHYSICAL_CONSTANTS_H
 
+/* Config parameters. */
+#include "../config.h"
+
+/* Local includes. */
 #include "units.h"
 
 /* physical constants in in defined programme units */
@@ -29,8 +33,11 @@ struct phys_const {
 
 /**
  * @brief Converts physical constants to the internal unit system
+ *
+ * @param us The current internal system of units.
+ * @param internal_const The physical constants to initialize.
  */
 void initPhysicalConstants(struct UnitSystem* us,
-                           struct phys_const* prog_const);
+                           struct phys_const* internal_const);
 
 #endif /* SWIFT_PHYSICAL_CONSTANTS_H */
diff --git a/src/potentials.c b/src/potentials.c
index 675ccaffe5ebc52539168e4df1ab5ecea206bfe2..0adc25bbd215aa80fc457d13b258bce10105db26 100644
--- a/src/potentials.c
+++ b/src/potentials.c
@@ -1,7 +1,36 @@
-#include "units.h"
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Tom Theuns (tom.theuns@durham.ac.uk)
+ *                    Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+
+/* Config parameters. */
+#include "../config.h"
+
+/* This object's header. */
 #include "potentials.h"
-#include "physical_constants.h"
 
+/**
+ * @brief Initialises the external potential properties in the internal system
+ * of units.
+ *
+ * @param us The current internal system of units
+ * @param potential The external potential properties to initialize
+ */
 void initPotentialProperties(struct UnitSystem* us,
                              struct external_potential* potential) {
   potential->point_mass.x =
diff --git a/src/potentials.h b/src/potentials.h
index 7d34d1b14b46cb746420841625be7a63a99d9e36..f753557bc49df7af8bf74a7ef39a6868998a2f96 100644
--- a/src/potentials.h
+++ b/src/potentials.h
@@ -1,6 +1,30 @@
+/*******************************************************************************
+ * This file is part of SWIFT.
+ * Copyright (c) 2016 Tom Theuns (tom.theuns@durham.ac.uk)
+ *                    Matthieu Schaller (matthieu.schaller@durham.ac.uk)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ ******************************************************************************/
+
 #ifndef SWIFT_POTENTIALS_H
 #define SWIFT_POTENTIALS_H
 
+/* Config parameters. */
+#include "../config.h"
+
+/* Local includes. */
 #include "physical_constants_cgs.h"
 #include "physical_constants.h"
 #include "units.h"
@@ -22,7 +46,6 @@ struct external_potential {
 #define External_Potential_Mass \
   (1e10 * SOLAR_MASS_IN_CGS / const_unit_mass_in_cgs)
 
-
 /**
  * @brief Computes the time-step due to the acceleration from a point mass
  *
@@ -55,7 +78,6 @@ __attribute__((always_inline))
   return 0.03f * sqrtf(a_2 / dota_2);
 }
 
-
 /**
  * @brief Computes the gravitational acceleration of a particle due to a point
  * mass