diff --git a/test/formats/index.js b/test/formats/index.js
index 8028a7e4ab..dee4f2c1be 100644
--- a/test/formats/index.js
+++ b/test/formats/index.js
@@ -165,6 +165,43 @@ describe("formats", () => {
 				});
 			}, /Missing required 'name' option for IIFE export/);
 		});
+
+		it('suggests using options.globals for default imports', () => {
+			const warnings = [];
+
+			svelte.compile(`
+				<script>
+					import _ from 'lodash';
+				</script>
+			`,
+				{
+					format: 'iife',
+					name: 'App',
+					onwarn: warning => {
+						warnings.push(warning);
+					}
+				}
+			);
+
+			assert.deepEqual(warnings, [{
+				message: `No name was supplied for imported module 'lodash'. Guessing '_', but you should use options.globals`
+			}]);
+		});
+
+		it('insists on options.globals for named imports', () => {
+			assert.throws(() => {
+				svelte.compile(`
+					<script>
+						import { fade } from 'svelte-transitions';
+					</script>
+				`,
+					{
+						format: 'iife',
+						name: 'App'
+					}
+				);
+			}, /Could not determine name for imported module 'svelte-transitions' – use options.globals/);
+		});
 	});
 
 	describe("umd", () => {