diff --git a/src/cell.h b/src/cell.h
index 3b931e12ce09303d353e2e2ddffe1eab7f77eeb5..199c901a7897b17ac275e5f8c4a5bcf7b68f5d73 100644
--- a/src/cell.h
+++ b/src/cell.h
@@ -117,8 +117,8 @@ struct cell {
   struct gpart *gparts;
 
   /* Pointers for the sorted indices. */
-  struct entry *sort, *gsort;
-  unsigned int sorted, gsorted;
+  struct entry *sort;
+  unsigned int sorted;
 
   /* Pointers to the next level of cells. */
   struct cell *progeny[8];
@@ -130,8 +130,8 @@ struct cell {
   struct cell *super;
 
   /* The task computing this cell's sorts. */
-  struct task *sorts, *gsorts;
-  int sortsize, gsortsize;
+  struct task *sorts;
+  int sortsize;
 
   /* The tasks computing this cell's density. */
   struct link *density, *gradient, *force, *grav;
diff --git a/src/riemann.h b/src/riemann.h
index 0191058e3ba856d7dcec42ba6185def3ee71d090..d0ae57a640e13c2098708735d6c34de70ebea5b0 100644
--- a/src/riemann.h
+++ b/src/riemann.h
@@ -27,6 +27,14 @@
 #include "stdio.h"
 #include "stdlib.h"
 
+/* Check that we use an ideal equation of state, since other equations of state
+   are not compatible with these Riemann solvers. */
+#ifndef EOS_IDEAL_GAS
+#error Currently there are no Riemann solvers that can handle the requested \
+       equation of state. Select an ideal gas equation of state if you want to \
+       use this hydro scheme!
+#endif
+
 #if defined(RIEMANN_SOLVER_EXACT)
 
 #define RIEMANN_SOLVER_IMPLEMENTATION "Exact Riemann solver (Toro 2009)"
diff --git a/src/runner.h b/src/runner.h
index 71e849d30233a07dbfadeb945a2b7c8ba56ab4a6..bc9e202b6a4bc62b385db5f233b3fb5f2ef08c18 100644
--- a/src/runner.h
+++ b/src/runner.h
@@ -29,26 +29,27 @@ extern const char runner_flip[27];
 struct cell;
 struct engine;
 
-/* A struct representing a runner's thread and its data. */
+/**
+ * @brief A struct representing a runner's thread and its data.
+ */
 struct runner {
 
-  /* The id of this thread. */
+  /*! The id of this thread. */
   int id;
 
-  /* The thread which it is running. */
+  /*! The actual thread which it is running. */
   pthread_t thread;
 
-  /* The queue to use to get tasks. */
+  /*! The queue to use to get tasks. */
   int cpuid, qid;
 
-  /* The underlying runner. */
+  /*! The engine owing this runner. */
   struct engine *e;
 };
 
 /* Function prototypes. */
 void runner_do_ghost(struct runner *r, struct cell *c);
 void runner_do_sort(struct runner *r, struct cell *c, int flag, int clock);
-void runner_do_gsort(struct runner *r, struct cell *c, int flag, int clock);
 void runner_do_kick(struct runner *r, struct cell *c, int timer);
 void runner_do_kick_fixdt(struct runner *r, struct cell *c, int timer);
 void runner_do_init(struct runner *r, struct cell *c, int timer);