diff --git a/hed/schema/schema_io/ontology_util.py b/hed/schema/schema_io/ontology_util.py
index da68197c6..5e3803355 100644
--- a/hed/schema/schema_io/ontology_util.py
+++ b/hed/schema/schema_io/ontology_util.py
@@ -72,6 +72,13 @@ def _get_hedid_range(schema_name, df_key):
     return set(range(final_start, final_end))
 
 
+# todo: Replace this once we no longer support < python 3.9
+def remove_prefix(text, prefix):
+    if text and text.startswith(prefix):
+        return text[len(prefix):]
+    return text
+
+
 def get_all_ids(df):
     """Returns a set of all unique hedIds in the dataframe
 
@@ -82,7 +89,7 @@ def get_all_ids(df):
         numbers(Set or None): None if this has no hed column, otherwise all unique numbers as a set.
     """
     if constants.hed_id in df.columns:
-        modified_df = df[constants.hed_id].str.removeprefix("HED_")
+        modified_df = df[constants.hed_id].apply(lambda x: remove_prefix(x, "HED_"))
         modified_df = pd.to_numeric(modified_df, errors="coerce").dropna().astype(int)
         return set(modified_df.unique())
     return None
diff --git a/hed/schema/schema_io/schema2df.py b/hed/schema/schema_io/schema2df.py
index 7917eb2f4..9c2b6c798 100644
--- a/hed/schema/schema_io/schema2df.py
+++ b/hed/schema/schema_io/schema2df.py
@@ -1,7 +1,7 @@
 """Allows output of HedSchema objects as .mediawiki format"""
 
 from hed.schema.hed_schema_constants import HedSectionKey, HedKey
-from hed.schema.schema_io.ontology_util import get_library_name_and_id
+from hed.schema.schema_io.ontology_util import get_library_name_and_id, remove_prefix
 from hed.schema.schema_io.schema2base import Schema2Base
 import pandas as pd
 import hed.schema.hed_schema_df_constants as constants
@@ -40,7 +40,7 @@ def _get_object_name_and_id(self, object_name, include_prefix=False):
             hed_id(str): The full formatted hed_id
         """
         prefix, obj_id = get_library_name_and_id(self._schema)
-        name = f"{prefix}{object_name.removeprefix('Hed')}"
+        name = f"{prefix}{remove_prefix(object_name, 'Hed')}"
         full_hed_id = self._get_object_id(object_name, obj_id, include_prefix)
         return name, full_hed_id
 
diff --git a/requirements.txt b/requirements.txt
index 9af8a52d8..ff3ca85e2 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,7 +1,7 @@
 defusedxml>=0.7.1
 inflect>=6.0.5
 jsonschema>=4.17.3
-matplotlib>=3.8.3
+matplotlib>=3
 numpy>=1.21.6
 openpyxl>=3.1.0
 pandas>=1.3.5