diff --git a/src/parser.ts b/src/parser.ts
index 625152e..c2aad28 100644
--- a/src/parser.ts
+++ b/src/parser.ts
@@ -394,20 +394,15 @@ export function parseFromProgram(
 			throw new Error('No types found');
 		}
 
-		// Typechecker only gives the type "any" if it's present in a union
-		// This means the type of "a" in {a?:any} isn't "any | undefined"
-		// So instead we check for the questionmark to detect optional types
-		let parsedType: t.Node | undefined = undefined;
-		if (
-			(type.flags & ts.TypeFlags.Any || type.flags & ts.TypeFlags.Unknown) &&
-			declaration &&
-			ts.isPropertySignature(declaration)
-		) {
-			parsedType = declaration.questionToken
-				? t.unionNode([t.undefinedNode(), t.anyNode()])
-				: t.anyNode();
-		} else {
-			parsedType = checkType(type, typeStack, symbol.getName());
+		let parsedType = checkType(type, typeStack, symbol.getName());
+
+		// In strict mode, the type of "a" in {a?: type} is "type | undefined",
+		// unless the type is "any", in which case TypeChecker only gives "any"
+		// Outside of strict mode, the type of "a" in {a?: type} is simply "type".
+		// To cover both of these cases we instead check for the questionmark
+		// to detect optional types
+		if (declaration && ts.isPropertySignature(declaration) && declaration.questionToken) {
+			parsedType = t.unionNode([t.undefinedNode(), parsedType]);
 		}
 
 		return t.propTypeNode(
@@ -440,7 +435,7 @@ export function parseFromProgram(
 					return t.elementNode('elementType');
 				}
 				case 'React.ReactNode': {
-					return t.unionNode([t.elementNode('node'), t.undefinedNode()]);
+					return t.unionNode([t.undefinedNode(), t.elementNode('node')]);
 				}
 				case 'Date':
 				case 'React.Component': {
diff --git a/test/index.test.ts b/test/index.test.ts
index 65c9375..9c7c4dc 100644
--- a/test/index.test.ts
+++ b/test/index.test.ts
@@ -10,99 +10,108 @@ const prettierConfig = prettier.resolveConfig.sync(path.join(__dirname, '../.pre
 
 const testCases = glob.sync('**/input.{d.ts,ts,tsx}', { absolute: true, cwd: __dirname });
 
-// Create program for all files to speed up tests
-const program = ttp.createProgram(
-	testCases,
-	ttp.loadConfig(path.resolve(__dirname, '../tsconfig.json'))
-);
+const tsModesConfigs = {
+	'default Typescript config': '../tsconfig.json',
+	'strict mode disabled': './tsconfig.nostrict.json',
+};
 
-for (const testCase of testCases) {
-	const dirname = path.dirname(testCase);
-	const testName = dirname.substr(__dirname.length + 1);
-	const astPath = path.join(dirname, 'output.json');
-	const outputPath = path.join(dirname, 'output.js');
-	const optionsPath = path.join(dirname, 'options.ts');
-	const inputJS = path.join(dirname, 'input.js');
+for (const [mode, configRelativePath] of Object.entries(tsModesConfigs)) {
+	describe(`given ${mode}`, () => {
+		// Create program for all files to speed up tests
+		const program = ttp.createProgram(
+			testCases,
+			ttp.loadConfig(path.resolve(__dirname, configRelativePath))
+		);
 
-	it(testName, () => {
-		const options: TestOptions = fs.existsSync(optionsPath) ? require(optionsPath).default : {};
+		for (const testCase of testCases) {
+			const dirname = path.dirname(testCase);
+			const testName = dirname.substr(__dirname.length + 1);
+			const astPath = path.join(dirname, 'output.json');
+			const outputPath = path.join(dirname, 'output.js');
+			const optionsPath = path.join(dirname, 'options.ts');
+			const inputJS = path.join(dirname, 'input.js');
 
-		const ast = ttp.parseFromProgram(testCase, program, options.parser);
+			it(testName, () => {
+				const options: TestOptions = fs.existsSync(optionsPath) ? require(optionsPath).default : {};
 
-		//#region Check AST matches
-		// propsFilename will be different depending on where the project is on disk
-		// Manually check that it's correct and then delete it
-		const newAST = ttp.programNode(
-			ast.body.map((component) => {
-				expect(component.propsFilename).toBe(testCase);
-				return { ...component, propsFilename: undefined };
-			})
-		);
+				const ast = ttp.parseFromProgram(testCase, program, options.parser);
 
-		if (fs.existsSync(astPath)) {
-			expect(newAST).toMatchObject(JSON.parse(fs.readFileSync(astPath, 'utf8')));
-		} else {
-			fs.writeFileSync(
-				astPath,
-				prettier.format(
-					JSON.stringify(newAST, (key, value) => {
-						// These are TypeScript internals that change depending on the number of symbols created during test
-						if (key === '$$id') {
-							return undefined;
-						}
-						return value;
-					}),
-					{
-						...prettierConfig,
-						filepath: astPath,
-					}
-				)
-			);
-		}
-		//#endregion
+				//#region Check AST matches
+				// propsFilename will be different depending on where the project is on disk
+				// Manually check that it's correct and then delete it
+				const newAST = ttp.programNode(
+					ast.body.map((component) => {
+						expect(component.propsFilename).toBe(testCase);
+						return { ...component, propsFilename: undefined };
+					})
+				);
 
-		let inputSource = null;
-		if (testCase.endsWith('.d.ts')) {
-			try {
-				inputSource = fs.readFileSync(inputJS, 'utf8');
-			} catch (error) {}
-		} else {
-			inputSource = ttp.ts.transpileModule(fs.readFileSync(testCase, 'utf8'), {
-				compilerOptions: {
-					target: ttp.ts.ScriptTarget.ESNext,
-					jsx: ttp.ts.JsxEmit.Preserve,
-				},
-			}).outputText;
-		}
+				if (fs.existsSync(astPath)) {
+					expect(newAST).toMatchObject(JSON.parse(fs.readFileSync(astPath, 'utf8')));
+				} else {
+					fs.writeFileSync(
+						astPath,
+						prettier.format(
+							JSON.stringify(newAST, (key, value) => {
+								// These are TypeScript internals that change depending on the number of symbols created during test
+								if (key === '$$id') {
+									return undefined;
+								}
+								return value;
+							}),
+							{
+								...prettierConfig,
+								filepath: astPath,
+							}
+						)
+					);
+				}
+				//#endregion
 
-		let result = '';
-		// For d.ts files we just generate the AST
-		if (!inputSource) {
-			result = ttp.generate(ast, options.generator);
-		}
-		// For .tsx? files we transpile them and inject the proptypes
-		else {
-			const injected = ttp.inject(ast, inputSource, options.injector);
-			if (!injected) {
-				throw new Error('Injection failed');
-			}
+				let inputSource: string | null = null;
+				if (testCase.endsWith('.d.ts')) {
+					try {
+						inputSource = fs.readFileSync(inputJS, 'utf8');
+					} catch (error) {}
+				} else {
+					inputSource = ttp.ts.transpileModule(fs.readFileSync(testCase, 'utf8'), {
+						compilerOptions: {
+							target: ttp.ts.ScriptTarget.ESNext,
+							jsx: ttp.ts.JsxEmit.Preserve,
+						},
+					}).outputText;
+				}
 
-			result = injected;
-		}
+				let result = '';
+				// For d.ts files we just generate the AST
+				if (!inputSource) {
+					result = ttp.generate(ast, options.generator);
+				}
+				// For .tsx? files we transpile them and inject the proptypes
+				else {
+					const injected = ttp.inject(ast, inputSource, options.injector);
+					if (!injected) {
+						throw new Error('Injection failed');
+					}
+
+					result = injected;
+				}
 
-		//#region Check generated and/or injected proptypes
-		const propTypes = prettier.format(result, {
-			...prettierConfig,
-			filepath: outputPath,
-		});
+				//#region Check generated and/or injected proptypes
+				const propTypes = prettier.format(result, {
+					...prettierConfig,
+					filepath: outputPath,
+				});
 
-		if (fs.existsSync(outputPath)) {
-			expect(propTypes.replace(/\r?\n/g, '\n')).toMatch(
-				fs.readFileSync(outputPath, 'utf8').replace(/\r?\n/g, '\n')
-			);
-		} else {
-			fs.writeFileSync(outputPath, propTypes);
+				if (fs.existsSync(outputPath)) {
+					expect(propTypes.replace(/\r?\n/g, '\n')).toMatch(
+						fs.readFileSync(outputPath, 'utf8').replace(/\r?\n/g, '\n')
+					);
+				} else {
+					fs.writeFileSync(outputPath, propTypes);
+				}
+				//#endregion
+			});
 		}
-		//#endregion
 	});
 }
diff --git a/test/injector/should-include-filename-based/output.json b/test/injector/should-include-filename-based/output.json
index bec47bd..dde55a5 100644
--- a/test/injector/should-include-filename-based/output.json
+++ b/test/injector/should-include-filename-based/output.json
@@ -1079,7 +1079,7 @@
 					"name": "children",
 					"propType": {
 						"type": "UnionNode",
-						"types": [{ "type": "ElementNode", "elementType": "node" }, { "type": "UndefinedNode" }]
+						"types": [{ "type": "UndefinedNode" }, { "type": "ElementNode", "elementType": "node" }]
 					},
 					"filenames": {}
 				},
@@ -2556,7 +2556,7 @@
 					"name": "children",
 					"propType": {
 						"type": "UnionNode",
-						"types": [{ "type": "ElementNode", "elementType": "node" }, { "type": "UndefinedNode" }]
+						"types": [{ "type": "UndefinedNode" }, { "type": "ElementNode", "elementType": "node" }]
 					},
 					"filenames": {}
 				}
diff --git a/test/reconcile-prop-types/output.json b/test/reconcile-prop-types/output.json
index e4d7144..cab4139 100644
--- a/test/reconcile-prop-types/output.json
+++ b/test/reconcile-prop-types/output.json
@@ -10,7 +10,7 @@
 					"name": "children",
 					"propType": {
 						"type": "UnionNode",
-						"types": [{ "type": "ElementNode", "elementType": "node" }, { "type": "UndefinedNode" }]
+						"types": [{ "type": "UndefinedNode" }, { "type": "ElementNode", "elementType": "node" }]
 					}
 				}
 			]
diff --git a/test/tsconfig.nostrict.json b/test/tsconfig.nostrict.json
new file mode 100644
index 0000000..c1f3188
--- /dev/null
+++ b/test/tsconfig.nostrict.json
@@ -0,0 +1,6 @@
+{
+	"extends": "../tsconfig.json",
+	"compilerOptions": {
+		"strict": false
+	}
+}