diff --git a/configure.in b/configure.in
index 96a9d16796..1c3b363277 100644
--- a/configure.in
+++ b/configure.in
@@ -563,30 +563,19 @@ AC_CHECK_LIB(supc++, main, XE_APPEND(-lsupc++, STATIC_CXXSUPPORT_LIB))
 AC_CHECK_LIB(gcc_eh, main, XE_APPEND(-lgcc_eh, STATIC_CXXSUPPORT_LIB))
 AC_SUBST(STATIC_CXXSUPPORT_LIB)
 
+AC_LANG_PUSH(C++)
 dnl check for INFINITY in math.h
-dnl _ISOC99_SOURCE is defined to emulate C++ compilation in plain-C conftest.c
-AC_TRY_COMPILE([#define _ISOC99_SOURCE 1
-#include <math.h>],
-    [double x = INFINITY;],
-    [AC_DEFINE(HAVE_INFINITY, 1,
-       [Define this if INFINITY is defined in math.h])])
+AC_COMPILE_IFELSE(
+	[AC_LANG_PROGRAM([[#include <math.h>]], [[double x = INFINITY;]])],
+	AC_DEFINE(HAVE_INFINITY, 1, [Define this if INFINITY is defined in math.h]))
 
 dnl check for va_copy() in stdarg.h
-dnl _ISOC99_SOURCE is defined to emulate C++ compilation in plain-C conftest.c
-AC_TRY_COMPILE([#define _ISOC99_SOURCE 1
-#include <stdarg.h>
-void vafun(const char* fmt, ...)
-{
-	va_list par, par2;
-	va_start(par, fmt);
-	va_copy(par2, par);
-	va_end(par2);
-	va_end(par);
-}
-],
-    [exit(0);],
-    [AC_DEFINE(HAVE_VA_COPY, 1,
-       [Define this if va_copy() is defined in stdarg.h])])
+AC_COMPILE_IFELSE(
+	[AC_LANG_PROGRAM([[#include <stdarg.h>
+		void vafun(const char* fmt, ...) {va_list par, par2; va_start(par, fmt); va_copy(par2, par); va_end(par2); va_end(par);}]], 
+		[[return 0;]])],
+	AC_DEFINE(HAVE_VA_COPY, 1, [Define this if va_copy() is defined in stdarg.h]))
+AC_LANG_POP(C++)
 
 dnl Check for functions
 AC_CHECK_FUNCS(gettimeofday)