diff --git a/data/bison.m4 b/data/bison.m4
index fac86f2a..a24b162c 100644
--- a/data/bison.m4
+++ b/data/bison.m4
@@ -58,6 +58,30 @@ This special exception was added by the Free Software Foundation in
 version 2.2 of Bison.])])
 
 
+## -------- ##
+## Output.  ##
+## -------- ##
+
+# b4_output_begin(FILE)
+# ---------------------
+# Enable output, i.e., send to diversion 0, expand after "#", and
+# generate the tag to output into FILE.  Must be followed by EOL.
+m4_define([b4_output_begin],
+[m4_changecom()
+m4_divert_push(0)dnl
+@output(m4_unquote([$1])@)@dnl
+])
+
+
+# b4_output_end()
+# ---------------
+# Output nothing, restore # as comment character (no expansions after #).
+m4_define([b4_output_end],
+[m4_divert_pop(0)
+m4_changecom([#])
+])
+
+
 ## ---------------- ##
 ## Error handling.  ##
 ## ---------------- ##
diff --git a/data/glr.c b/data/glr.c
index b6aa545c..cdefd507 100644
--- a/data/glr.c
+++ b/data/glr.c
@@ -179,13 +179,10 @@ m4_define([b4_shared_declarations],
 ## Output files.  ##
 ## -------------- ##
 
-# We do want M4 expansion after # for CPP macros.
-m4_changecom()
-m4_divert_push(0)dnl
-@output(b4_parser_file_name@)@
+b4_output_begin([b4_parser_file_name])
 b4_copyright([Skeleton implementation for Bison GLR parsers in C],
-             [2002-2012])
-[
+             [2002-2012])[
+
 /* C GLR parser skeleton written by Paul Hilfinger.  */
 
 ]b4_identification
@@ -2571,17 +2568,17 @@ yypdumpstack (yyGLRStack* yystackp)
 }
 #endif
 ]b4_epilogue[]dnl
-dnl
-dnl glr.cc produces its own header.
-dnl
+b4_output_end()
+
+# glr.cc produces its own header.
 m4_if(b4_skeleton, ["glr.c"],
 [b4_defines_if(
-[@output(b4_spec_defines_file@)@
+[b4_output_begin([b4_spec_defines_file])
 b4_copyright([Skeleton interface for Bison GLR parsers in C],
              [2002-2012])[
 
 ]b4_cpp_guard_open([b4_spec_defines_file])[
 ]b4_shared_declarations[
 ]b4_cpp_guard_close([b4_spec_defines_file])[
-]])])dnl
-m4_divert_pop(0)
+]b4_output_end()
+])])
diff --git a/data/glr.cc b/data/glr.cc
index 0e53d619..49b4fa10 100644
--- a/data/glr.cc
+++ b/data/glr.cc
@@ -230,8 +230,7 @@ m4_defn([b4_parse_param]))],
 m4_include(b4_pkgdatadir/[glr.c])
 m4_popdef([b4_parse_param])
 
-m4_divert_push(0)
-@output(b4_spec_defines_file@)@
+b4_output_begin([b4_spec_defines_file])
 b4_copyright([Skeleton interface for Bison GLR parsers in C++],
              [2002-2006, 2009-2012])[
 
@@ -344,4 +343,4 @@ b4_percent_define_flag_if([[global_tokens_and_yystype]],
 ]b4_namespace_close[
 ]b4_percent_code_get([[provides]])[
 ]b4_cpp_guard_close([b4_spec_defines_file])[
-]m4_divert_pop(0)
+]b4_output_end()
diff --git a/data/lalr1.cc b/data/lalr1.cc
index e45b2e1f..237b246f 100644
--- a/data/lalr1.cc
+++ b/data/lalr1.cc
@@ -30,11 +30,8 @@ b4_percent_define_ifdef([[api.location.type]], [],
   m4_include(b4_pkgdatadir/[location.cc])])
 m4_include(b4_pkgdatadir/[stack.hh])
 
-# We do want M4 expansion after # for CPP macros.
-m4_changecom()
-m4_divert_push(0)dnl
 b4_defines_if(
-[@output(b4_spec_defines_file@)@
+[b4_output_begin([b4_spec_defines_file])
 b4_copyright([Skeleton interface for Bison LALR(1) parsers in C++],
              [2002-2012])
 [
@@ -265,8 +262,11 @@ b4_user_stype
 ])[
 ]b4_percent_code_get([[provides]])[
 ]b4_cpp_guard_close([b4_spec_defines_file])
-])dnl
-@output(b4_parser_file_name@)@
+b4_output_end()
+])
+
+
+b4_output_begin([b4_parser_file_name])
 b4_copyright([Skeleton implementation for Bison LALR(1) parsers in C++],
              [2002-2012])
 b4_percent_code_get([[top]])[]dnl
@@ -1140,4 +1140,4 @@ b4_error_verbose_if([int yystate, int yytoken],
 
 ]b4_namespace_close[
 ]b4_epilogue[]dnl
-m4_divert_pop(0)
+b4_output_end()
diff --git a/data/lalr1.java b/data/lalr1.java
index d1410a10..e961fc5b 100644
--- a/data/lalr1.java
+++ b/data/lalr1.java
@@ -22,8 +22,7 @@ m4_ifval(m4_defn([b4_symbol_destructors]),
         [b4_fatal([%s: %%destructor does not make sense in Java], [b4_skeleton])],
         [])
 
-m4_divert_push(0)dnl
-@output(b4_parser_file_name@)@
+b4_output_begin([b4_parser_file_name])
 b4_copyright([Skeleton implementation for Bison LALR(1) parsers in Java],
              [2007-2012])
 
@@ -925,4 +924,4 @@ b4_percent_code_get[]dnl
 }
 
 b4_epilogue
-m4_divert_pop(0)dnl
+b4_output_end()
diff --git a/data/location.cc b/data/location.cc
index 49f5f349..58182a34 100644
--- a/data/location.cc
+++ b/data/location.cc
@@ -15,10 +15,8 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-# We do want M4 expansion after # for CPP macros.
-m4_changecom()
-m4_divert_push(0)dnl
-@output(b4_dir_prefix[]position.hh@)@
+
+b4_output_begin([b4_dir_prefix[]position.hh])
 b4_copyright([Positions for Bison parsers in C++],
              [2002-2007, 2009-2012])[
 
@@ -148,7 +146,10 @@ b4_copyright([Positions for Bison parsers in C++],
 
 ]b4_namespace_close[
 ]b4_cpp_guard_close([b4_dir_prefix[]position.hh])
-@output(b4_dir_prefix[]location.hh@)@
+b4_output_end()
+
+
+b4_output_begin([b4_dir_prefix[]location.hh])
 b4_copyright([Locations for Bison parsers in C++],
              [2002-2007, 2009-2012])[
 
@@ -292,5 +293,4 @@ b4_copyright([Locations for Bison parsers in C++],
 ]b4_namespace_close[
 
 ]b4_cpp_guard_close([b4_dir_prefix[]location.hh])
-m4_divert_pop(0)
-m4_changecom([#])
+b4_output_end()
diff --git a/data/stack.hh b/data/stack.hh
index ddedc79b..ab1049c1 100644
--- a/data/stack.hh
+++ b/data/stack.hh
@@ -18,10 +18,7 @@
 m4_pushdef([b4_copyright_years],
            [2002-2012])
 
-# We do want M4 expansion after # for CPP macros.
-m4_changecom()
-m4_divert_push(0)dnl
-@output(b4_dir_prefix[]stack.hh@)@
+b4_output_begin([b4_dir_prefix[]stack.hh])
 b4_copyright([Stack handling for Bison parsers in C++],
              [2002-2012])[
 
@@ -119,6 +116,6 @@ b4_copyright([Stack handling for Bison parsers in C++],
 ]b4_namespace_close[
 
 ]b4_cpp_guard_close([b4_dir_prefix[]stack.hh])
-m4_divert_pop(0)
-m4_popdef([b4_copyright_years])dnl
-m4_changecom([#])
+b4_output_end()
+
+m4_popdef([b4_copyright_years])
diff --git a/data/yacc.c b/data/yacc.c
index 0f315523..810e2b21 100644
--- a/data/yacc.c
+++ b/data/yacc.c
@@ -326,14 +326,12 @@ m4_define([b4_shared_declarations],
 ]b4_cpp_guard_close([b4_spec_defines_file])[]dnl
 ])
 
+
 ## -------------- ##
 ## Output files.  ##
 ## -------------- ##
 
-# We do want M4 expansion after # for CPP macros.
-m4_changecom()
-m4_divert_push(0)dnl
-@output(b4_parser_file_name@)@
+b4_output_begin([b4_parser_file_name])
 b4_copyright([Bison implementation for Yacc-like parsers in C],
              [1984, 1989-1990, 2000-2012])[
 
@@ -2052,11 +2050,13 @@ yypushreturn:]])[
 
 
 ]b4_epilogue[]dnl
+b4_output_end()
+
 b4_defines_if(
-[@output(b4_spec_defines_file@)@
-b4_copyright([Bison interface for Yacc-like parsers in C],
-             [1984, 1989-1990, 2000-2012])[
+[b4_output_begin([b4_spec_defines_file])[
+]b4_copyright([Bison interface for Yacc-like parsers in C],
+              [1984, 1989-1990, 2000-2012])[
 
 ]b4_shared_declarations[
-]])dnl b4_defines_if
-m4_divert_pop(0)
+]b4_output_end()
+])