diff --git a/minimalmodbus.py b/minimalmodbus.py
index 8d22676..3226d86 100644
--- a/minimalmodbus.py
+++ b/minimalmodbus.py
@@ -1512,7 +1512,7 @@ def _communicate(self, request: bytes, number_of_bytes_to_read: int) -> bytes:
                 " Timeout for reading: {:.1f} ms.\n"
             ).format(
                 _describe_bytes(answer),
-                roundtrip_time,
+                roundtrip_time * _SECONDS_TO_MILLISECONDS,
                 timeout_time,
             )
             self._print_debug(text)