diff --git a/configure.ac b/configure.ac
index 0832753..6dd80a5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -11,25 +11,31 @@ AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_MACRO_DIR([m4])
 
 # Checks for programs.
+AC_PROG_CXX
 AC_PROG_CC
 AC_PROG_CC_C99
 AC_PROG_LIBTOOL
 AM_PROG_CC_C_O
+AC_PROG_RANLIB
 
 # Checks for libraries.
 AC_CHECK_LIB([json], [json_object_new_object], [],
 	     [AC_MSG_ERROR([json-c library not found], [1])])
 
 # Checks for header files.
-AC_CHECK_HEADERS([stdarg.h string.h stdlib.h stdio.h sys/types.h json/json.h])
+AC_CHECK_HEADERS([stdarg.h string.h stdlib.h stdio.h unistd.h syslog.h
+		  sys/types.h json/json.h])
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_HEADER_STDBOOL
 AC_C_INLINE
+AC_TYPE_PID_T
 AC_TYPE_SIZE_T
 
 # Checks for library functions.
-#AC_CHECK_FUNCS([memchr])
+AC_FUNC_FORK
+AC_FUNC_MALLOC
+AC_CHECK_FUNCS([memset])
 
 AC_CONFIG_FILES([Makefile tests/Makefile])
 AC_OUTPUT