diff --git a/RTCP/Cobalt/InputProc/src/Delays/Delays.cc b/RTCP/Cobalt/InputProc/src/Delays/Delays.cc
index 9e8c220c3cb0900792934970b3b2626971861f42..1f5b73aebf24b6265208da0ebe79b80b4e2ae0c7 100644
--- a/RTCP/Cobalt/InputProc/src/Delays/Delays.cc
+++ b/RTCP/Cobalt/InputProc/src/Delays/Delays.cc
@@ -154,6 +154,9 @@ namespace LOFAR
     bool Delays::test()
     {
       try {
+        ScopedLock lock(casacoreMutex);
+        ScopedDelayCancellation dc;
+
         // set up a converter
         MDirection::Types dirType;