diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 76ad861..4b4e35b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -31,6 +31,8 @@ jobs:
         with:
           python-version: 3.8
       - name: Install dependencies
-        run: python3.8 -m pip install nox
+        run: |
+            sudo apt-get install --yes pandoc
+            python3.8 -m pip install nox
       - name: Build documentation
         run: nox -s docs
diff --git a/eland/field_mappings.py b/eland/field_mappings.py
index 7226d41..00cb2f2 100644
--- a/eland/field_mappings.py
+++ b/eland/field_mappings.py
@@ -42,8 +42,6 @@ from pandas.core.dtypes.inference import is_list_like
 if TYPE_CHECKING:
     from elasticsearch import Elasticsearch
 
-    from eland import DataFrame
-
 
 ES_FLOAT_TYPES: Set[str] = {"double", "float", "half_float", "scaled_float"}
 ES_INTEGER_TYPES: Set[str] = {"long", "integer", "short", "byte"}
@@ -463,7 +461,7 @@ class FieldMappings:
         return cls.ES_DTYPE_TO_PD_DTYPE.get(es_dtype, "object")
 
     @staticmethod
-    def _pd_dtype_to_es_dtype(pd_dtype):
+    def _pd_dtype_to_es_dtype(pd_dtype) -> Optional[str]:
         """
         Mapping pandas dtypes to Elasticsearch dtype
         --------------------------------------------
@@ -479,7 +477,7 @@ class FieldMappings:
         category NA NA Finite list of text values
         ```
         """
-        es_dtype = None
+        es_dtype: Optional[str] = None
 
         # Map all to 64-bit - TODO map to specifics: int32 -> int etc.
         if is_float_dtype(pd_dtype):
@@ -501,7 +499,7 @@ class FieldMappings:
 
     @staticmethod
     def _generate_es_mappings(
-        dataframe: "DataFrame", es_type_overrides: Optional[Mapping[str, str]] = None
+        dataframe: "pd.DataFrame", es_type_overrides: Optional[Mapping[str, str]] = None
     ) -> Dict[str, Dict[str, Dict[str, Any]]]:
         """Given a pandas dataframe, generate the associated Elasticsearch mapping
 
@@ -536,8 +534,19 @@ class FieldMappings:
           }
         }
         """
+        es_dtype: str
+
+        mapping_props: Dict[str, Any] = {}
+
+        if es_type_overrides is not None:
+            non_existing_columns: List[str] = [
+                key for key in es_type_overrides.keys() if key not in dataframe.columns
+            ]
+            if non_existing_columns:
+                raise KeyError(
+                    f"{repr(non_existing_columns)[1:-1]} column(s) not in given dataframe"
+                )
 
-        mapping_props = {}
         for column, dtype in dataframe.dtypes.iteritems():
             if es_type_overrides is not None and column in es_type_overrides:
                 es_dtype = es_type_overrides[column]
diff --git a/eland/tests/dataframe/test_utils_pytest.py b/eland/tests/dataframe/test_utils_pytest.py
index e1b57c3..87586ee 100644
--- a/eland/tests/dataframe/test_utils_pytest.py
+++ b/eland/tests/dataframe/test_utils_pytest.py
@@ -19,6 +19,7 @@
 
 import numpy as np
 import pandas as pd
+import pytest
 
 import eland as ed
 from eland.field_mappings import FieldMappings
@@ -139,3 +140,28 @@ class TestDataFrameUtils(TestData):
 
         # This test calls the same method so is redundant
         # assert_pandas_eland_frame_equal(pd_df, self.ed_flights())
+
+    def test_es_type_override_error(self):
+
+        df = self.pd_flights().filter(
+            ["AvgTicketPrice", "Cancelled", "dayOfWeek", "timestamp", "DestCountry"]
+        )
+
+        index_name = "test_es_type_override"
+
+        match = "'DistanceKilometers', 'DistanceMiles' column(s) not in given dataframe"
+        with pytest.raises(KeyError, match=match):
+            ed.pandas_to_eland(
+                df,
+                ES_TEST_CLIENT,
+                index_name,
+                es_if_exists="replace",
+                es_refresh=True,
+                use_pandas_index_for_es_ids=False,
+                es_type_overrides={
+                    "AvgTicketPrice": "long",
+                    "DistanceKilometers": "text",
+                    "DistanceMiles": "text",
+                },
+            )
+            ES_TEST_CLIENT.indices.delete(index=index_name)
diff --git a/noxfile.py b/noxfile.py
index 3f3a170..a515ce3 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -19,7 +19,6 @@ import os
 import subprocess
 from pathlib import Path
 
-import elasticsearch
 import nox
 
 BASE_DIR = Path(__file__).parent
@@ -126,6 +125,8 @@ def docs(session):
     # See if we have an Elasticsearch cluster active
     # to rebuild the Jupyter notebooks with.
     try:
+        import elasticsearch
+
         es = elasticsearch.Elasticsearch("localhost:9200")
         es.info()
         if not es.indices.exists("flights"):