diff --git a/data_tables/logical_types.py b/data_tables/logical_types.py
index a76bfdb07..6f381a095 100644
--- a/data_tables/logical_types.py
+++ b/data_tables/logical_types.py
@@ -121,7 +121,8 @@ def get_logical_types():
 
 
 def str_to_logical_type(logical_str):
-    logical_types_dict = get_logical_types()
+    logical_str = logical_str.lower()
+    logical_types_dict = {ltype_name.lower(): ltype for ltype_name, ltype in get_logical_types().items()}
 
     if logical_str in logical_types_dict:
         return logical_types_dict[logical_str]
diff --git a/data_tables/tests/data_column/test_data_column.py b/data_tables/tests/data_column/test_data_column.py
index cc147ea4e..acd1036d8 100644
--- a/data_tables/tests/data_column/test_data_column.py
+++ b/data_tables/tests/data_column/test_data_column.py
@@ -66,8 +66,9 @@ def test_invalid_logical_type(sample_series):
     with pytest.raises(TypeError, match=error_message):
         DataColumn(sample_series, int)
 
-    with pytest.raises(TypeError, match=error_message):
-        DataColumn(sample_series, 'naturallanguage')
+    error_message = "String naturalllanguage is not a valid logical type"
+    with pytest.raises(ValueError, match=error_message):
+        DataColumn(sample_series, 'naturalllanguage')
 
 
 def test_semantic_type_errors(sample_series):
diff --git a/data_tables/tests/logical_types/test_logical_types.py b/data_tables/tests/logical_types/test_logical_types.py
index b3d65c4e9..f17376fbf 100644
--- a/data_tables/tests/logical_types/test_logical_types.py
+++ b/data_tables/tests/logical_types/test_logical_types.py
@@ -2,7 +2,8 @@
     Boolean,
     Categorical,
     LogicalType,
-    get_logical_types
+    get_logical_types,
+    str_to_logical_type
 )
 
 
@@ -28,3 +29,11 @@ def test_get_logical_types():
         assert logical_types[logical_type.type_string] == logical_type
 
     assert len(logical_types) == 2 * len(all_types)
+
+
+def test_str_to_logical_type():
+    all_types = LogicalType.__subclasses__()
+
+    for logical_type in all_types:
+        assert str_to_logical_type(logical_type.__name__) == logical_type
+        assert str_to_logical_type(logical_type.type_string) == logical_type