diff --git a/fastlite/kw.py b/fastlite/kw.py
index 109d878..3fc7d4e 100644
--- a/fastlite/kw.py
+++ b/fastlite/kw.py
@@ -4,6 +4,8 @@
 from sqlite_minutils.db import Database,Table,DEFAULT,ForeignKeysType,Default,Queryable,NotFoundError
 from enum import Enum
 
+class MissingPrimaryKey(Exception): pass
+
 opt_bool = Union[bool, Default, None]
 
 def database(path, wal=True)->Any:
@@ -203,13 +205,14 @@ def upsert(
     columns: Union[Dict[str, Any], Default, None]=DEFAULT,
     strict: Union[bool, Default]|None=DEFAULT,
     **kwargs) -> Table:
+    record = _process_row(record)
+    record = {**record, **kwargs}
+    if not record: return {}    
     if pk==DEFAULT:
         assert len(self.pks)==1
         pk = self.pks[0]
-    if not record: record={}
-    record = _process_row(record)
-    record = {**record, **kwargs}
-    last_pk = record[pk]
+    try: last_pk = record[pk]
+    except KeyError as e: raise MissingPrimaryKey(e.args[0])
     self._orig_upsert(
         record=record, pk=pk, foreign_keys=foreign_keys, column_order=column_order, not_null=not_null,
         defaults=defaults, hash_id=hash_id, hash_id_columns=hash_id_columns, alter=alter,
diff --git a/nbs/test_upsert.ipynb b/nbs/test_upsert.ipynb
new file mode 100644
index 0000000..e1d2326
--- /dev/null
+++ b/nbs/test_upsert.ipynb
@@ -0,0 +1,467 @@
+{
+ "cells": [
+  {
+   "cell_type": "markdown",
+   "id": "fd325418",
+   "metadata": {},
+   "source": [
+    "# Test Upsert Operations"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "417f2c4e",
+   "metadata": {},
+   "source": [
+    "## Setup"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "ad470f25",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from fastlite import *"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "e4788661",
+   "metadata": {},
+   "source": [
+    "Note: Make sure to use fastlite's `database()` here"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "97dd1b48",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "db = database(':memory:')"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "5102a3ac",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "class People: id: int; name: str"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "9188c149",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "people = db.create(People, pk='id')"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "6c99cbae",
+   "metadata": {},
+   "source": [
+    "## Test Single Upserts"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "dbc67ac6",
+   "metadata": {},
+   "source": [
+    "Here we test `upsert()`"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "a0673d88",
+   "metadata": {},
+   "source": [
+    "### Test Cases for `upsert()` Where Nothing Is Inserted"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "eb45e038",
+   "metadata": {},
+   "source": [
+    "Test that calling `upsert()` without any parameters doesn't change anything, and returns nothing"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "fba0c4f7",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "{}"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "people.upsert()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "0355fe0a",
+   "metadata": {},
+   "source": [
+    "Test None doesn't change anything."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "ace59c88",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "count = people.count\n",
+    "assert people.upsert(None) == {}\n",
+    "assert people.count == count"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "2ab1795b",
+   "metadata": {},
+   "source": [
+    "Test empty dict doesn't change anything "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "a93ec70a",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "count = people.count\n",
+    "assert people.upsert({}) == {}\n",
+    "assert people.count == count"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "79cd5186",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Test empty dataclass doesn't change anything\n",
+    "PersonDC = people.dataclass()\n",
+    "count = people.count\n",
+    "assert people.upsert(PersonDC()) == {}\n",
+    "assert people.count == count"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "aa988175",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Test empty class instance doesn't change anything\n",
+    "class EmptyPerson: pass\n",
+    "count = people.count\n",
+    "assert people.upsert(EmptyPerson()) == {}\n",
+    "assert people.count == count"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "811bc666",
+   "metadata": {},
+   "source": [
+    "### Single Insert Types"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "157baebb",
+   "metadata": {},
+   "source": [
+    "Test upsert with keyword argument without id. Result should be a MissingPrimaryKey error"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "1fdd0aaf",
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "Correct throwing of MissingPrimaryError\n"
+     ]
+    }
+   ],
+   "source": [
+    "try: people.upsert(name='Alice')\n",
+    "except MissingPrimaryKey: print('Correct throwing of MissingPrimaryError')"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "e1300c26",
+   "metadata": {},
+   "source": [
+    "Use upsert to insert a new record via a dataclass. Since it can't find the id, it adds the record"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "de73d39a",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "person = people.upsert(People(name='Alice', id=people.count+1))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "447e13c9",
+   "metadata": {},
+   "source": [
+    "Test upsert that updates with dataclass. Since it can find the id, it updates the record."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "c736aa0f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "assert people.upsert(People(name='Bobba', id=person.id)).name == 'Bobba'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "77e6e4c0",
+   "metadata": {},
+   "source": [
+    "Use upsert to insert a new record via a class. Since it can't find the id, it adds the record"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "dd80748f",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "count = people.count\n",
+    "class Student: pass\n",
+    "student = Student()\n",
+    "student.name = 'Daniel Greenfeld'\n",
+    "student.id = people.count+1\n",
+    "\n",
+    "assert people.upsert(student).name == 'Daniel Greenfeld'\n",
+    "assert people.count == count+1"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "0b4eb6df",
+   "metadata": {},
+   "source": [
+    "Test upsert that updates with class. Since it can find the id, it updates the record."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "cfd90ab0",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "count = people.count\n",
+    "student = Student()\n",
+    "student.name = 'Daniel Roy Greenfeld'\n",
+    "student.id = person.id\n",
+    "\n",
+    "assert people.upsert(student).name == 'Daniel Roy Greenfeld'\n",
+    "assert people.count == count"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "26a9c38a",
+   "metadata": {},
+   "source": [
+    "### None and Empty String Handling"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "37ad998d",
+   "metadata": {},
+   "source": [
+    "Test upserting a record with name set to None. First assert checks the method result, the second assert tests that the database was altered correctly."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "5a968d13",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "result = people.upsert(People(name=None, id=person.id))\n",
+    "assert result.name is None\n",
+    "assert people[person.id].name is None"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "dd0c180d",
+   "metadata": {},
+   "source": [
+    "Test with empty string."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "92d53608",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "result = people.upsert(People(name='', id=person.id))\n",
+    "assert result.name == ''\n",
+    "assert people[person.id].name == ''"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "d855c6a8",
+   "metadata": {},
+   "source": [
+    "### Other Cases"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "1ee61d32",
+   "metadata": {},
+   "source": [
+    "Test upserts with special characters. Let's do updates first"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "972bab86",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "assert people.upsert(People(name='O\\'Connor', id=person.id)).name == \"O'Connor\"\n",
+    "assert people[person.id].name == \"O'Connor\"\n",
+    "assert people.upsert(People(name='José', id=person.id)).name == 'José'\n",
+    "assert people[person.id].name == \"José\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "b1069ca8",
+   "metadata": {},
+   "source": [
+    "Now test special characters with upserts that insert."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "2b702435",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "person = people.upsert(People(name='O\\'Connor', id=people.count+1))\n",
+    "assert person.name == \"O'Connor\"\n",
+    "assert people[person.id].name == \"O'Connor\"\n",
+    "person = people.upsert(People(name='José', id=people.count+1))\n",
+    "assert person.name == \"José\"\n",
+    "assert people[person.id].name == \"José\""
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "f27e986a",
+   "metadata": {},
+   "source": [
+    "Test dict upsert"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "45a4c2aa",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "assert people.upsert({'name': 'Dict Test', 'id': person.id}).name == 'Dict Test'"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "f1209e4b",
+   "metadata": {},
+   "source": [
+    "Test that extra fields raise `sqlite3.OperationalError`"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "07c034e9",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from sqlite3 import OperationalError"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "963008b6",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "try:\n",
+    "    p = people.upsert(dict(name='Extra', age=25, title='Dr', id=person.id))\n",
+    "except OperationalError as e:\n",
+    "    assert e.args[0] == 'no such column: age'"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "python3",
+   "language": "python",
+   "name": "python3"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}