diff --git a/lib/cpp/configure.ac b/lib/cpp/configure.ac
index d9a66da..25b6152 100644
--- a/lib/cpp/configure.ac
+++ b/lib/cpp/configure.ac
@@ -14,6 +14,8 @@
 
 AC_FUNC_MALLOC
 
+AC_FUNC_MEMCMP
+
 AC_FUNC_REALLOC
 
 AC_FUNC_SELECT_ARGTYPES