diff --git a/singer_sdk/helpers/_flattening.py b/singer_sdk/helpers/_flattening.py
index 078391e73..29fa68b23 100644
--- a/singer_sdk/helpers/_flattening.py
+++ b/singer_sdk/helpers/_flattening.py
@@ -443,7 +443,7 @@ def _flatten_record(
             nan_strategies = {
                 "fail": False,
                 "allow": True,
-                "convert_null": None,
+                "convert_null": False,
             }
 
             ignore_nan = nan_strategy == "convert_null"