diff --git a/src/ModelTree.cc b/src/ModelTree.cc
index 41bed024ef26df24163dd96f549c225f54628a0f..6f554ea26565c751e7e73b9caa74f86149be7443 100644
--- a/src/ModelTree.cc
+++ b/src/ModelTree.cc
@@ -1964,7 +1964,10 @@ ModelTree::initializeMEXCompilationWorkers(int numworkers, const filesystem::pat
             lk.lock();
             mex_compilation_ongoing.erase(output);
             if (r)
-              mex_compilation_failed.insert(output);
+              {
+                cout << cmd.str() << endl;
+                mex_compilation_failed.insert(output);
+              } 
             else
               mex_compilation_done.insert(output);
             /* The object just compiled may be a prerequisite for several