diff --git a/Makefile b/Makefile
index f39a721..4eb7d7b 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,13 @@ include $(ARCH_MAKE)
 AR      ?= ar
 ARFLAGS ?= cru
 RANLIB  ?= ranlib
-PP      ?= cpp -E -P -C
+
+# Sadly the preprocessor for fortran is a bit of a pain.
+# -C is needed to disregard C-comments (the operator // is a comment!?!)
+# -nostdinc is needed to not include standard includes (which are C comments)
+# -E only preprocess, do not try and compile
+# -P do not add line markers
+PP ?= cpp -E -P -C -nostdinc
 
 VPATH   ?= $(shell pwd)
 
diff --git a/dictionary_pp.F90 b/dictionary_pp.F90
index 7f0ccef..d289b14 100644
--- a/dictionary_pp.F90
+++ b/dictionary_pp.F90
@@ -92,7 +92,7 @@ module dictionary
   public :: operator(.IN.)
 
   ! check whether key not exists in dictionary
-  !> Returns .not. ('key. .in. dict)
+  !> Returns .not. ('key' .in. dict)
   interface operator( .NIN. )
      module procedure nin
   end interface operator( .NIN. )