diff --git a/Framework/Core/include/Framework/OutputSpec.h b/Framework/Core/include/Framework/OutputSpec.h
index 0f4974ef88702..da1e5df5a2bad 100644
--- a/Framework/Core/include/Framework/OutputSpec.h
+++ b/Framework/Core/include/Framework/OutputSpec.h
@@ -73,6 +73,8 @@ struct OutputSpec {
     return origin == that.origin && description == that.description && subSpec == that.subSpec &&
            lifetime == that.lifetime;
   };
+
+  friend std::ostream& operator<<(std::ostream& stream, OutputSpec const& arg);
 };
 
 } // namespace framework
diff --git a/Framework/Core/src/StreamOperators.cxx b/Framework/Core/src/StreamOperators.cxx
index 3d4a0793a8122..cd3cb88c67934 100644
--- a/Framework/Core/src/StreamOperators.cxx
+++ b/Framework/Core/src/StreamOperators.cxx
@@ -8,8 +8,11 @@
 // granted to it by virtue of its status as an Intergovernmental Organization
 // or submit itself to any jurisdiction.
 
-#include <ostream>
 #include "Framework/InputSpec.h"
+#include "Framework/OutputSpec.h"
+
+#include <ostream>
+#include <string>
 
 namespace o2
 {
@@ -23,5 +26,12 @@ std::ostream& operator<<(std::ostream& stream, o2::framework::InputSpec const& a
   return stream;
 }
 
+std::ostream& operator<<(std::ostream& stream, o2::framework::OutputSpec const& arg)
+{
+  // FIXME: should have stream operators for the header fields
+  stream << arg.binding.value << " {" << arg.origin.as<std::string>() << ":" << arg.description.as<std::string>() << ":" << arg.subSpec << "}";
+  return stream;
+}
+
 } // namespace framework
 } // namespace o2