diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 14e2776fe2d6111d633a6ab766235e799e004474..fc92184d08ccd07a0ad9823d7514da6443b23a07 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2001-10-07  Joseph S. Myers  <jsm28@cam.ac.uk>
+
+	* doc/c-tree.texi, doc/tm.texi: Consistently put NULL and
+	NULL_TREE inside @code.
+
 2001-10-07  Joseph S. Myers  <jsm28@cam.ac.uk>
 
 	* doc/gcc.texi: Document consistent style of "32-bit",
diff --git a/gcc/doc/c-tree.texi b/gcc/doc/c-tree.texi
index 350c9bca2457b3eed43ecba105e50500b481ccbe..e36090abcdd202b320c5dec6b28df2f351c722c5 100644
--- a/gcc/doc/c-tree.texi
+++ b/gcc/doc/c-tree.texi
@@ -500,7 +500,7 @@ arguments.
 
 Note that in C (but not in C++) a function declared like @code{void f()}
 is an unprototyped function taking a variable number of arguments; the
-@code{TYPE_ARG_TYPES} of such a function will be NULL@.
+@code{TYPE_ARG_TYPES} of such a function will be @code{NULL}.
 
 @item METHOD_TYPE
 Used to represent the type of a non-static member function.  Like a
@@ -1308,7 +1308,7 @@ This predicate holds if the function an overloaded
 @findex WHILE_COND
 
 A function that has a definition in the current translation unit will
-have a non-NULL @code{DECL_INITIAL}.  However, back ends should not make
+have a non-@code{NULL} @code{DECL_INITIAL}.  However, back ends should not make
 use of the particular value given by @code{DECL_INITIAL}.
 
 The @code{DECL_SAVED_TREE} macro will give the complete body of the
@@ -1423,8 +1423,8 @@ fields.
 @item CASE_LABEL
 
 Use to represent a @code{case} label, range of @code{case} labels, or a
-@code{default} label.  If @code{CASE_LOW} is NULL_TREE, then this is a a
-@code{default} label.  Otherwise, if @code{CASE_HIGH} is NULL_TREE, then
+@code{default} label.  If @code{CASE_LOW} is @code{NULL_TREE}, then this is a a
+@code{default} label.  Otherwise, if @code{CASE_HIGH} is @code{NULL_TREE}, then
 this is an ordinary @code{case} label.  In this case, @code{CASE_LOW} is
 an expression giving the value of the label.  Both @code{CASE_LOW} and
 @code{CASE_HIGH} are @code{INTEGER_CST} nodes.  These values will have
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index cd4ec28aebbdbca8e06824aa97623cdb02d864a3..193a060c72fca203d464cde284c6ead5ffa1d248 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -849,7 +849,7 @@ function pointers below.
 @findex init_machine_status
 @item   init_machine_status
 This is a @code{void (*)(struct function *)} function pointer.  If this
-pointer is non-NULL it will be called once per function, before function
+pointer is non-@code{NULL} it will be called once per function, before function
 compilation starts, in order to allow the target to perform any target
 specific initialisation of the @code{struct function} structure.  It is
 intended that this would be used to initialise the @code{machine} of
@@ -858,14 +858,14 @@ that structure.
 @findex free_machine_status
 @item   free_machine_status
 This is a @code{void (*)(struct function *)} function pointer.  If this
-pointer is non-NULL it will be called once per function, after the
+pointer is non-@code{NULL} it will be called once per function, after the
 function has been compiled, in order to allow any memory allocated
 during the @code{init_machine_status} function call to be freed.
 
 @findex mark_machine_status
 @item   mark_machine_status
 This is a @code{void (*)(struct function *)} function pointer.  If this
-pointer is non-NULL it will be called once per function in order to mark
+pointer is non-@code{NULL} it will be called once per function in order to mark
 any data items in the @code{struct machine_function} structure which
 need garbage collection.
 
@@ -6575,7 +6575,7 @@ buffer in which to store the name; its length is as long as
 
 The argument @var{is_inst} specifies whether the method is an instance
 method or a class method; @var{class_name} is the name of the class;
-@var{cat_name} is the name of the category (or NULL if the method is not
+@var{cat_name} is the name of the category (or @code{NULL} if the method is not
 in a category); and @var{sel_name} is the name of the selector.
 
 On systems where the assembler can handle quoted names, you can use this