diff --git a/config-msvc.h b/config-msvc.h
index 0260927ce..4db9efae2 100644
--- a/config-msvc.h
+++ b/config-msvc.h
@@ -47,7 +47,6 @@
 #define HAVE_ACCESS 1
 #define HAVE_CHDIR 1
 #define HAVE_CHSIZE 1
-#define HAVE_CPP_VARARG_MACRO_ISO 1
 #define HAVE_CTIME 1
 #define HAVE_EVP_CIPHER_CTX_SET_KEY_LENGTH 1
 #define HAVE_IN_PKTINFO 1
diff --git a/m4/ax_varargs.m4 b/m4/ax_varargs.m4
deleted file mode 100644
index c295d21f4..000000000
--- a/m4/ax_varargs.m4
+++ /dev/null
@@ -1,77 +0,0 @@
-dnl @synopsis AX_CPP_VARARG_MACRO_GCC
-dnl
-dnl Test if the preprocessor understands GNU GCC-style vararg macros.
-dnl If it does, defines HAVE_CPP_VARARG_MACRO_GCC to 1.
-dnl
-dnl @version
-dnl @author James Yonan <jim@yonan.net>, Matthias Andree <matthias.andree@web.de>
-AC_DEFUN([AX_CPP_VARARG_MACRO_GCC], [dnl
-	AS_VAR_PUSHDEF([VAR], [ax_cv_cpp_vararg_macro_gcc])dnl
-	AC_CACHE_CHECK(
-		[for GNU GCC vararg macro support],
-		[VAR],
-		[AC_COMPILE_IFELSE(
-			[AC_LANG_PROGRAM(
-				[[
-#define macro(a, b...) func(a, b)
-int func(int a, int b, int c);
-				]],
-				[[
-int i = macro(1, 2, 3);
-				]]
-			)],
-			[VAR=yes],
-			[VAR=no]
-		)]
-	)dnl
-
-	AS_VAR_IF(
-		[VAR],
-		[yes],
-		[AC_DEFINE(
-			[HAVE_CPP_VARARG_MACRO_GCC],
-			[1], 
-			[Define to 1 if your compiler supports GNU GCC-style variadic macros]
-		)]
-	)dnl
-	AS_VAR_POPDEF([VAR])dnl
-])
-
-dnl @synopsis AX_CPP_VARARG_MACRO_ISO
-dnl
-dnl Test if the preprocessor understands ISO C 1999 vararg macros.
-dnl If it does, defines HAVE_CPP_VARARG_MACRO_ISO to 1.
-dnl
-dnl @version
-dnl @author James Yonan <jim@yonan.net>, Matthias Andree <matthias.andree@web.de>
-AC_DEFUN([AX_CPP_VARARG_MACRO_ISO], [dnl
-	AS_VAR_PUSHDEF([VAR],[ax_cv_cpp_vararg_macro_iso])dnl
-	AC_CACHE_CHECK(
-		[for ISO C 1999 vararg macro support],
-		[VAR],
-		[AC_COMPILE_IFELSE(
-			[AC_LANG_PROGRAM(
-				[[
-#define macro(a, ...) func(a, __VA_ARGS__)
-int func(int a, int b, int c);
-				]],
-				[[
-int i = macro(1, 2, 3);
-				]]
-			)],
-			[VAR=yes],
-			[VAR=no]
-		)]
-	)dnl
-
-	AS_VAR_IF(
-		[VAR],
-		[yes],
-		[AC_DEFINE(
-			[HAVE_CPP_VARARG_MACRO_ISO],
-			[1], 
-			[Define to 1 if your compiler supports ISO C99 variadic macros]
-		)]
-	)dnl
-	AS_VAR_POPDEF([VAR])dnl
-])
diff --git a/src/openvpn/error.c b/src/openvpn/error.c
index 0ecbfc330..e6f7ff0ff 100644
--- a/src/openvpn/error.c
+++ b/src/openvpn/error.c
@@ -236,26 +236,22 @@ x_msg_va(const unsigned int flags, const char *format, va_list arglist)
 
     void usage_small(void);
 
-#ifndef HAVE_VARARG_MACROS
     /* the macro has checked this otherwise */
     if (!msg_test(flags))
     {
         return;
     }
-#endif
 
     e = openvpn_errno();
 
     /*
      * Apply muting filter.
      */
-#ifndef HAVE_VARARG_MACROS
     /* the macro has checked this otherwise */
     if (!dont_mute(flags))
     {
         return;
     }
-#endif
 
     gc_init(&gc);
 
diff --git a/src/openvpn/error.h b/src/openvpn/error.h
index eaedf172c..1a5521654 100644
--- a/src/openvpn/error.h
+++ b/src/openvpn/error.h
@@ -146,33 +146,12 @@ bool dont_mute(unsigned int flags);
 /* Macro to ensure (and teach static analysis tools) we exit on fatal errors */
 #define EXIT_FATAL(flags) do { if ((flags) & M_FATAL) {_exit(1);}} while (false)
 
-#if defined(HAVE_CPP_VARARG_MACRO_ISO) && !defined(__LCLINT__)
-#define HAVE_VARARG_MACROS
 #define msg(flags, ...) do { if (msg_test(flags)) {x_msg((flags), __VA_ARGS__);} EXIT_FATAL(flags); } while (false)
 #ifdef ENABLE_DEBUG
 #define dmsg(flags, ...) do { if (msg_test(flags)) {x_msg((flags), __VA_ARGS__);} EXIT_FATAL(flags); } while (false)
 #else
 #define dmsg(flags, ...)
 #endif
-#elif defined(HAVE_CPP_VARARG_MACRO_GCC) && !defined(__LCLINT__)
-#define HAVE_VARARG_MACROS
-#define msg(flags, args ...) do { if (msg_test(flags)) {x_msg((flags), args);} EXIT_FATAL(flags); } while (false)
-#ifdef ENABLE_DEBUG
-#define dmsg(flags, args ...) do { if (msg_test(flags)) {x_msg((flags), args);} EXIT_FATAL(flags); } while (false)
-#else
-#define dmsg(flags, args ...)
-#endif
-#else  /* if defined(HAVE_CPP_VARARG_MACRO_ISO) && !defined(__LCLINT__) */
-#if !PEDANTIC
-#ifdef _MSC_VER
-#pragma message("this compiler appears to lack vararg macros which will cause a significant degradation in efficiency")
-#else
-#warning this compiler appears to lack vararg macros which will cause a significant degradation in efficiency (you can ignore this warning if you are using LCLINT)
-#endif
-#endif
-#define msg x_msg
-#define dmsg x_msg
-#endif /* if defined(HAVE_CPP_VARARG_MACRO_ISO) && !defined(__LCLINT__) */
 
 void x_msg(const unsigned int flags, const char *format, ...)
 #ifdef __GNUC__
diff --git a/src/tapctl/error.h b/src/tapctl/error.h
index 924cbbe89..cea50ba52 100644
--- a/src/tapctl/error.h
+++ b/src/tapctl/error.h
@@ -67,7 +67,6 @@ bool dont_mute(unsigned int flags);
 #endif
 #define EXIT_FATAL(flags) do { if ((flags) & M_FATAL) {_exit(1);}} while (false)
 
-#define HAVE_VARARG_MACROS
 #define msg(flags, ...) do { if (msg_test(flags)) {x_msg((flags), __VA_ARGS__);} EXIT_FATAL(flags); } while (false)
 #ifdef ENABLE_DEBUG
 #define dmsg(flags, ...) do { if (msg_test(flags)) {x_msg((flags), __VA_ARGS__);} EXIT_FATAL(flags); } while (false)