diff --git a/src/biocommons/example/__main__.py b/src/biocommons/example/__main__.py
index a360fc6..f2e0505 100644
--- a/src/biocommons/example/__main__.py
+++ b/src/biocommons/example/__main__.py
@@ -23,7 +23,7 @@ def main():  # pragma: no cover
     )
 
     quote = marvin.get_quote()
-    _logger.warning("Got quote from Marvin (len=%s)" % (len(quote),))
+    _logger.warning("Got quote from Marvin (len=%s)", len(quote))
 
     print("Marvin says:")
     print(quote)
diff --git a/src/biocommons/example/marvin.py b/src/biocommons/example/marvin.py
index 461eca5..d8f4a6f 100644
--- a/src/biocommons/example/marvin.py
+++ b/src/biocommons/example/marvin.py
@@ -40,6 +40,6 @@ def get_quote() -> str:
 
     quote = random.choice(quotes)
 
-    _logger.info("Got quote from Marvin (len=%s)" % (len(quote),))
+    _logger.info("Got quote from Marvin (len=%s)", len(quote))
 
     return quote