-CHECK_FUNCTION_EXISTS(snprintf HAVE_SNPRINTF)
-CHECK_FUNCTION_EXISTS(vsnprintf HAVE_VSNPRINTF)
-CHECK_FUNCTION_EXISTS(asprintf HAVE_ASPRINTF)
-CHECK_FUNCTION_EXISTS(vasprintf HAVE_VASPRINTF)
+
+CHECK_SYMBOL_EXISTS(snprintf stdio.h HAVE_SNPRINTF)
+CHECK_SYMBOL_EXISTS(vsnprintf stdio.h HAVE_VSNPRINTF)
+CHECK_SYMBOL_EXISTS(asprintf stdio.h HAVE_ASPRINTF)
+CHECK_SYMBOL_EXISTS(vasprintf stdio.h HAVE_VASPRINTF)
+