diff --git a/doc/examples/cryptoki-sign-demo.cxx b/doc/examples/cryptoki-sign-demo.cxx
index 393cc73..056593e 100644
--- a/doc/examples/cryptoki-sign-demo.cxx
+++ b/doc/examples/cryptoki-sign-demo.cxx
@@ -91,7 +91,7 @@ int main(int argc, char** argv) try {
                           id);
       if (keys.size()!=1) {
         std::cerr<<"**** ERROR: No private key: "<<keys.size()<<std::endl;
-        return;
+        return 1;
       }
       std::cout<<"Signing ..."<<std::endl;
 #ifndef MRW__OLD_PRE11_COMPILER