diff --git a/m4/ax_cxx_compile_stdcxx_11.m4 b/m4/ax_cxx_compile_stdcxx_11.m4
index 7ad01e03..20c8b120 100644
--- a/m4/ax_cxx_compile_stdcxx_11.m4
+++ b/m4/ax_cxx_compile_stdcxx_11.m4
@@ -76,6 +76,8 @@ m4_define([_AX_CXX_COMPILE_STDCXX_11_testbody], [[
         template<typename T>
         void func(member<T>*) {}
 
+        void test();
+
         void test() {
             func<foo>(0);
         }