diff --git a/src/errors/check-constraint-violation.js b/src/errors/check-constraint-violation.js
index d886747..3c1f4e7 100644
--- a/src/errors/check-constraint-violation.js
+++ b/src/errors/check-constraint-violation.js
@@ -27,7 +27,7 @@ module.exports = {
 			throw new Error("Encountered unknown error format");
 		}
 
-		let [_, query, table, constraint] = messageMatch;
+		let [_, query, _table, _constraint] = messageMatch;
 
 		let columns = getColumns(query);
 
diff --git a/src/errors/not-null-constraint-violation.js b/src/errors/not-null-constraint-violation.js
index cdfd6fb..8981554 100644
--- a/src/errors/not-null-constraint-violation.js
+++ b/src/errors/not-null-constraint-violation.js
@@ -20,7 +20,7 @@ module.exports = {
 		);
 	},
 	convert: function convertError(error) {
-		let [_, query, column] = messageRegex.exec(error.message);
+		let [_, query, _column] = messageRegex.exec(error.message);
 
 		return new NotNullConstraintViolationError(`Missing required value for column '${error.column}' in table '${error.table}'`, {
 			originalError: error,
diff --git a/src/errors/undefined-column.js b/src/errors/undefined-column.js
index 457ef2d..dcde6ef 100644
--- a/src/errors/undefined-column.js
+++ b/src/errors/undefined-column.js
@@ -4,7 +4,6 @@ const { create } = require("error-chain");
 const pgErrorCodes = require("pg-error-codes");
 
 const DatabaseError = require("../database-error.js");
-const getTable = require("../get-table");
 
 let UndefinedColumnError = create("UndefinedColumnError", { inheritsFrom: DatabaseError });
 
diff --git a/src/get-columns.js b/src/get-columns.js
index 0b4678c..9efa3c5 100644
--- a/src/get-columns.js
+++ b/src/get-columns.js
@@ -5,7 +5,7 @@ let updateRegex = /^update "[^"]+" set (.+) where/;
 let updateColumnRegex = /^"([^"]+)"/;
 
 module.exports = function getColumns(query) {
-	let match, columns;
+	let match;
 
 	if (match = insertRegex.exec(query)) {
 		return match[1].split(",").map((columnName) => {
diff --git a/test/create-tables/check-constraint-violation.js b/test/create-tables/check-constraint-violation.js
index 24d7809..ddd9603 100644
--- a/test/create-tables/check-constraint-violation.js
+++ b/test/create-tables/check-constraint-violation.js
@@ -1,7 +1,5 @@
 'use strict';
 
-const Promise = require("bluebird");
-
 module.exports = {
 	up: function createCheckConstraintViolationTable(knex, errorHandler) {
 		return knex.schema.createTable("check_constraint_violation", (table) => {
diff --git a/test/create-tables/index.js b/test/create-tables/index.js
index 2134ba9..cdee9ab 100644
--- a/test/create-tables/index.js
+++ b/test/create-tables/index.js
@@ -12,7 +12,7 @@ let tables = [
 	require("./not-null-constraint-violation")
 ];
 
-let noop = function noop(err) {
+let noop = function noop(_err) {
 	// Do nothing.
 };