diff --git a/tracetools_trace/tracetools_trace/tools/lttng.py b/tracetools_trace/tracetools_trace/tools/lttng.py
index d358475..2f0b5eb 100644
--- a/tracetools_trace/tracetools_trace/tools/lttng.py
+++ b/tracetools_trace/tracetools_trace/tools/lttng.py
@@ -14,6 +14,8 @@
 
 """Interface for tracing with LTTng."""
 
+import sys
+
 from typing import List
 from typing import Optional
 
@@ -23,6 +25,7 @@ try:
     _lttng = lttng_impl
 except ImportError:
     # Fall back on empty functions
+    print('Warning: lttng Python package not found', file=sys.stderr)
     from . import lttng_stub
 
     _lttng = lttng_stub