diff --git a/Internal.h b/Internal.h
index 0d4f791..6380afa 100644
--- a/Internal.h
+++ b/Internal.h
@@ -658,7 +658,9 @@ template <class ConflictSetImpl> struct TestDriver {
       assert(iter == keys.end());
       assert(i == numPointWrites + numRangeWrites);
 
+#if DEBUG_VERBOSE && !defined(NDEBUG)
       fprintf(stderr, "Write @ %" PRId64 "\n", v);
+#endif
 
       CALLGRIND_START_INSTRUMENTATION;
       cs.addWrites(writes, numPointWrites + numRangeWrites, v);