diff --git a/index.js b/index.js
index 6aec9bc..29adfb5 100644
--- a/index.js
+++ b/index.js
@@ -164,14 +164,16 @@ function initializeTextBuffer(buffer) {
 					const lastRow = buffer.getLineCount() - 1;
 
 					if (buffer.isRowBlank(lastRow)) {
-						const previousNonBlankRow = buffer.previousNonBlankRow(lastRow);
+						let stripStart = buffer.previousNonBlankRow(lastRow);
 
+						if (settings.insert_final_newline === true) {
+							stripStart += 1;
+						}
 						// Strip empty lines from the end
-						if (previousNonBlankRow < lastRow) {
-							buffer.deleteRows(previousNonBlankRow + 1, lastRow);
+						if (stripStart < lastRow) {
+							buffer.deleteRows(stripStart + 1, lastRow);
 						}
-					}
-					if (settings.insert_final_newline === true) {
+					} else if (settings.insert_final_newline === true) {
 						buffer.append('\n');
 					}
 				}
diff --git a/spec/iss121-spec.js b/spec/iss121-spec.js
new file mode 100644
index 0000000..38582b6
--- /dev/null
+++ b/spec/iss121-spec.js
@@ -0,0 +1,78 @@
+/** @babel */
+/* eslint-env jasmine, atomtest */
+
+/*
+  This file contains verifying specs for:
+  https://github.com/sindresorhus/atom-editorconfig/issues/121
+
+  Due to a bad implementation of the `insert_final_newline`-logic the final newline
+  is unecessarily stripped and appended even if a single final newline already exists.
+  This messes the undo-history up.
+*/
+
+import fs from 'fs';
+import path from 'path';
+
+const projectRoot = path.join(__dirname, 'fixtures');
+const filePath = path.join(
+	projectRoot,
+	`test.${path.basename(__filename).split('-').shift()}`
+);
+
+describe('editorconfig', () => {
+	let textEditor;
+	const textWithOneFinalNewline = `
+This is a text
+with a lot of lines,
+which have a lot of
+trailing spaces.\n`;
+
+	beforeEach(() => {
+		waitsForPromise(() =>
+			Promise.all([
+				atom.packages.activatePackage('editorconfig'),
+				atom.workspace.open(filePath)
+			]).then(results => {
+				textEditor = results[1];
+			})
+		);
+	});
+
+	afterEach(() => {
+		// remove the created fixture, if it exists
+		runs(() => {
+			fs.stat(filePath, (err, stats) => {
+				if (!err && stats.isFile()) {
+					fs.unlink(filePath);
+				}
+			});
+		});
+
+		waitsFor(() => {
+			try {
+				return fs.statSync(filePath).isFile() === false;
+			} catch (err) {
+				return true;
+			}
+		}, 5000, `removed ${filePath}`);
+	});
+
+	describe('Atom being set to insert a final newline', () => {
+		beforeEach(() => {
+			Object.assign(textEditor.getBuffer().editorconfig.settings, {
+				trim_trailing_whitespace: true, // eslint-disable-line camelcase
+				insert_final_newline: true // eslint-disable-line camelcase
+			});
+		});
+
+		it('should strip not extend the undo-history if a final newline already exists', () => {
+			const buffer = textEditor.getBuffer();
+
+			textEditor.setText(textWithOneFinalNewline);
+
+			const checkpoint = buffer.createCheckpoint();
+			textEditor.save();
+			expect(buffer.getChangesSinceCheckpoint(checkpoint).length).toEqual(0);
+		});
+	});
+});