diff --git a/sqlite_utils/utils.py b/sqlite_utils/utils.py
index 8968a05..d086ddb 100644
--- a/sqlite_utils/utils.py
+++ b/sqlite_utils/utils.py
@@ -13,7 +13,8 @@ def suggest_column_types(records):
     all_column_types = {}
     for record in records:
         for key, value in record.items():
-            all_column_types.setdefault(key, set()).add(type(value))
+            if value is not None:
+                all_column_types.setdefault(key, set()).add(type(value))
     column_types = {}
     for key, types in all_column_types.items():
         if len(types) == 1:
diff --git a/tests/test_suggest_column_types.py b/tests/test_suggest_column_types.py
index 9427444..a392c09 100644
--- a/tests/test_suggest_column_types.py
+++ b/tests/test_suggest_column_types.py
@@ -7,14 +7,20 @@ from sqlite_utils.utils import suggest_column_types
     "records,types",
     [
         ([{"a": 1}], {"a": int}),
+        ([{"a": 1}, {"a": None}], {"a": int}),
         ([{"a": "baz"}], {"a": str}),
+        ([{"a": "baz"}, {"a": None}], {"a": str}),
         ([{"a": 1.2}], {"a": float}),
+        ([{"a": 1.2}, {"a": None}], {"a": float}),
         ([{"a": [1]}], {"a": str}),
+        ([{"a": [1]}, {"a": None}], {"a": str}),
         ([{"a": (1,)}], {"a": str}),
         ([{"a": {"b": 1}}], {"a": str}),
+        ([{"a": {"b": 1}}, {"a": None}], {"a": str}),
         ([{"a": OrderedDict({"b": 1})}], {"a": str}),
         ([{"a": 1}, {"a": 1.1}], {"a": float}),
         ([{"a": b"b"}], {"a": bytes}),
+        ([{"a": b"b"}, {"a": None}], {"a": bytes}),
     ],
 )
 def test_suggest_column_types(records, types):