diff --git a/camb/recombination.py b/camb/recombination.py
index 01aa2439..81747b5e 100644
--- a/camb/recombination.py
+++ b/camb/recombination.py
@@ -62,9 +62,6 @@ class HyRec(RecombinationModel):
     `HyRec <https://github.com/nanoomlee/HYREC-2>`_ recombination model.
     To use this, the library must be build with HyRec installed and RECOMBINATION_FILES including hyrec in the Makefile.
 
-    You will need to edit HyRec Makefile to add -fPIC compiler flag to CCFLAG (for gcc), and rename "dtauda\_"
-    in history.c to "exported_dtauda"
-
     """
     _fortran_class_module_ = 'HyRec'
     _fortran_class_name_ = 'THyRec'
diff --git a/fortran/equations.f90 b/fortran/equations.f90
index 133ee9bc..1a35a2bf 100644
--- a/fortran/equations.f90
+++ b/fortran/equations.f90
@@ -35,6 +35,9 @@ module GaugeInterface
     implicit none
     public
 
+    ! Equations and relation to synchronous gauge variables documented in the notes:
+    ! https://cosmologist.info/notes/CAMB.pdf
+
     !Description of this file. Change if you make modifications.
     character(LEN=*), parameter :: Eqns_name = 'cdm_gauge'