Index: contrib/flex/src/flex.skl
===================================================================
--- contrib/flex/src/flex.skl
+++ contrib/flex/src/flex.skl
@@ -216,12 +216,6 @@
 
 /* First, we deal with  platform-specific or compiler-specific issues. */
 
-#if defined(__FreeBSD__)
-#include <sys/cdefs.h>
-#else
-#define	__dead2
-#endif
-
 /* begin standard C headers. */
 %if-c-only
 #include <stdio.h>
@@ -653,7 +647,7 @@
 static yy_state_type yy_get_previous_state ( M4_YY_PROTO_ONLY_ARG );
 static yy_state_type yy_try_NUL_trans ( yy_state_type current_state  M4_YY_PROTO_LAST_ARG);
 static int yy_get_next_buffer ( M4_YY_PROTO_ONLY_ARG );
-static void yynoreturn yy_fatal_error ( const char* msg M4_YY_PROTO_LAST_ARG ) __dead2;
+static void yynoreturn yy_fatal_error ( const char* msg M4_YY_PROTO_LAST_ARG );
 ]])
 
 %endif
Index: tools/build/bootstrap-m4/inittokenizer.c
===================================================================
--- tools/build/bootstrap-m4/inittokenizer.c
+++ tools/build/bootstrap-m4/inittokenizer.c
@@ -14,16 +14,6 @@
 
 /* First, we deal with  platform-specific or compiler-specific issues. */
 
-#if defined(__FreeBSD__)
-#ifndef __STDC_LIMIT_MACROS
-#define	__STDC_LIMIT_MACROS
-#endif
-#include <sys/cdefs.h>
-#include <stdint.h>
-#else
-#define	__dead2
-#endif
-
 /* begin standard C headers. */
 #include <stdio.h>
 #include <string.h>
Index: usr.bin/lex/initscan.c
===================================================================
--- usr.bin/lex/initscan.c
+++ usr.bin/lex/initscan.c
@@ -16,12 +16,6 @@
 
 /* First, we deal with  platform-specific or compiler-specific issues. */
 
-#if defined(__FreeBSD__)
-#include <sys/cdefs.h>
-#else
-#define	__dead2
-#endif
-
 /* begin standard C headers. */
 #include <stdio.h>
 #include <string.h>
Index: usr.bin/lex/initskel.c
===================================================================
--- usr.bin/lex/initskel.c
+++ usr.bin/lex/initskel.c
@@ -447,16 +447,6 @@
   "",
   "/* First, we deal with  platform-specific or compiler-specific issues. */",
   "",
-  "#if defined(__FreeBSD__)",
-  "#ifndef __STDC_LIMIT_MACROS",
-  "#define	__STDC_LIMIT_MACROS",
-  "#endif",
-  "#include <sys/cdefs.h>",
-  "#include <stdint.h>",
-  "#else",
-  "#define	__dead2",
-  "#endif",
-  "",
   "/* begin standard C headers. */",
   "%if-c-only",
   "#include <stdio.h>",
@@ -948,7 +938,7 @@
   "static yy_state_type yy_get_previous_state ( M4_YY_PROTO_ONLY_ARG );",
   "static yy_state_type yy_try_NUL_trans ( yy_state_type current_state  M4_YY_PROTO_LAST_ARG);",
   "static int yy_get_next_buffer ( M4_YY_PROTO_ONLY_ARG );",
-  "static void yynoreturn yy_fatal_error ( const char* msg M4_YY_PROTO_LAST_ARG ) __dead2;",
+  "static void yynoreturn yy_fatal_error ( const char* msg M4_YY_PROTO_LAST_ARG );",
   "]])",
   "",
   "%endif",