diff --git a/src/tools/Exception.h b/src/tools/Exception.h
index 0792da371a..4b008fda12 100644
--- a/src/tools/Exception.h
+++ b/src/tools/Exception.h
@@ -381,10 +381,11 @@ class ExceptionTypeError :
 #ifdef NDEBUG
 
 // These are the versions used when compiling with NDEBUG flag.
-// The condition is always true, so that the rest of the statement
-// should be optimized away.
-#define plumed_dbg_assert(test) plumed_assert(true)
-#define plumed_dbg_massert(test,msg) plumed_massert(true,msg)
+// The if constexpr(false) gurarantees that the compiler will optimize away the assertion
+// We are not using an empty macro becasue the user may want to use the << operator
+
+#define plumed_dbg_assert(test) if constexpr(false) plumed_assert(true)
+#define plumed_dbg_massert(test,msg) if constexpr(false) plumed_massert(true,msg)
 
 #else