diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9f83c78..891ea83 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 - Fixed an issue where sending lots of subscriptions could cause a `BufferError`
 - Fixed an issue where `Historical.batch.download` was slow
 - Fixed an issue where `Historical.timeseries.get_range` was slow
+- Fixed an issue where reading a DBN file with non-empty metadata symbol mappings and mixed `SType` would cause an error when mapping symbols (credit: Jakob Lövhall)
 
 ## 0.24.1 - 2023-12-15
 
diff --git a/databento/common/symbology.py b/databento/common/symbology.py
index 0a25775..1dceffb 100644
--- a/databento/common/symbology.py
+++ b/databento/common/symbology.py
@@ -242,8 +242,8 @@ def insert_metadata(self, metadata: Metadata) -> None:
             # Nothing to do
             return
 
-        stype_in = SType(metadata.stype_in)
-        stype_out = SType(metadata.stype_out)
+        stype_in = SType(metadata.stype_in) if metadata.stype_in is not None else None
+        stype_out = SType(metadata.stype_out) if metadata.stype_out is not None else None
 
         for symbol_in, entries in metadata.mappings.items():
             for entry in entries:
diff --git a/tests/test_common_symbology.py b/tests/test_common_symbology.py
index ca9ae25..bac23b9 100644
--- a/tests/test_common_symbology.py
+++ b/tests/test_common_symbology.py
@@ -166,7 +166,7 @@ def create_metadata(
     dataset: str = "UNIT.TEST",
     start: int = UNDEF_TIMESTAMP,
     end: int = UNDEF_TIMESTAMP,
-    stype_in: SType = SType.RAW_SYMBOL,
+    stype_in: SType | None = SType.RAW_SYMBOL,
     stype_out: SType = SType.INSTRUMENT_ID,
     schema: Schema = Schema.TRADES,
     limit: int | None = None,
@@ -198,10 +198,18 @@ def test_instrument_map(
     assert instrument_map._data == {}
 
 
+@pytest.mark.parametrize(
+    "stype_in",
+    [
+        SType.RAW_SYMBOL,
+        None,
+    ],
+)
 def test_instrument_map_insert_metadata(
     instrument_map: InstrumentMap,
     start_date: pd.Timestamp,
     end_date: pd.Timestamp,
+    stype_in: SType | None,
 ) -> None:
     """
     Test the insertion of DBN Metadata.
@@ -224,6 +232,7 @@ def test_instrument_map_insert_metadata(
     ]
 
     metadata = create_metadata(
+        stype_in=stype_in,
         mappings=mappings,
     )