diff --git a/src/helpers.js b/src/helpers.js
index 9450797..2722430 100644
--- a/src/helpers.js
+++ b/src/helpers.js
@@ -20,7 +20,7 @@ function getLoaderOptions(pluginState, loaderOptions) {
     }
 
     if (typeof options.polyfills === 'string') {
-        options.modules = [options.polyfills];
+        options.polyfills = [options.polyfills];
     } else if (!Array.isArray(options.polyfills) || options.polyfills.length === 0) {
         throw new Error('[webpack-polyfill-injector] You need to specify the `polyfills` option!');
     }
diff --git a/test/test.js b/test/test.js
index b156c4e..bac6d81 100644
--- a/test/test.js
+++ b/test/test.js
@@ -302,92 +302,121 @@ describe('webpack-polyfill-injector', () => {
 
 
     describe('When configuring multiple entry modules', () => {
-        let state; // eslint-disable-line init-declarations
-        before(async () => {
-            state = await test({
-                entry: {
-                    app: `webpack-polyfill-injector?${JSON.stringify({
-                        modules: [
-                            './test/fixtures/entry.js',
-                            './test/fixtures/entry2.js',
-                        ],
-                        polyfills: ['Promise'],
-                    })}!`,
-                    other: `webpack-polyfill-injector?${JSON.stringify({
-                        modules: [
-                            './test/fixtures/entry3.js',
-                        ],
-                        polyfills: ['Array.prototype.find'],
-                    })}!`,
-                },
-                plugins: [new PolyfillInjectorPlugin({polyfills: ['Promise', 'Array.prototype.find']})],
-                testHooks: {
-                    executeBundle({window}) {
-                        window.eval('delete window.Promise');
-                        window.eval('delete window.Array.prototype.find');
+        describe('with different polyfills', () => {
+            let state; // eslint-disable-line init-declarations
+            before(async () => {
+                state = await test({
+                    entry: {
+                        app: `webpack-polyfill-injector?${JSON.stringify({
+                            modules: [
+                                './test/fixtures/entry.js',
+                                './test/fixtures/entry2.js',
+                            ],
+                            polyfills: ['Promise'],
+                        })}!`,
+                        other: `webpack-polyfill-injector?${JSON.stringify({
+                            modules: [
+                                './test/fixtures/entry3.js',
+                            ],
+                            polyfills: ['Array.prototype.find'],
+                        })}!`,
+                    },
+                    plugins: [new PolyfillInjectorPlugin({polyfills: ['Promise', 'Array.prototype.find']})],
+                    testHooks: {
+                        executeBundle({window}) {
+                            window.eval('delete window.Promise');
+                            window.eval('delete window.Array.prototype.find');
+                        },
                     },
-                },
+                });
             });
-        });
 
-        it('creates two assets: app.js, other.js, polyfills.js, polyfills-1.js', () => {
-            const assets = state.stats.compilation.assets;
-            expect(Object.keys(assets)).to.have.lengthOf(4);
-            expect(assets).to.have.property('app.js');
-            expect(assets).to.have.property('polyfills.js');
-            expect(assets).to.have.property('other.js');
-            expect(assets).to.have.property('polyfills-1.js');
-        });
+            it('creates four assets: app.js, other.js, polyfills.js, polyfills-1.js', () => {
+                const assets = state.stats.compilation.assets;
+                expect(Object.keys(assets)).to.have.lengthOf(4);
+                expect(assets).to.have.property('app.js');
+                expect(assets).to.have.property('polyfills.js');
+                expect(assets).to.have.property('other.js');
+                expect(assets).to.have.property('polyfills-1.js');
+            });
 
-        it('does not mix the polyfill configurations', () => {
-            const polyfills2 = state.fs.readFileSync('/polyfills-1.js', 'utf-8');
-            expect(state.polyfillsFile).to.contain('Promise');
-            expect(state.polyfillsFile).to.not.contain('Array.prototype.find');
-            expect(polyfills2).to.not.contain('Promise');
-            expect(polyfills2).to.contain('Array.prototype.find');
-        });
+            it('does not mix the polyfill configurations', () => {
+                const polyfills2 = state.fs.readFileSync('/polyfills-1.js', 'utf-8');
+                expect(state.polyfillsFile).to.contain('Promise');
+                expect(state.polyfillsFile).to.not.contain('Array.prototype.find');
+                expect(polyfills2).to.not.contain('Promise');
+                expect(polyfills2).to.contain('Array.prototype.find');
+            });
 
-        it('does not guard the polyfills', () => {
-            const polyfills2 = state.fs.readFileSync('/polyfills-1.js', 'utf-8');
-            expect(state.polyfillsFile).to.not.contain(`'Promise' in this`);
-            expect(polyfills2).to.not.contain(`'find' in Array.prototype`);
-        });
+            it('does not guard the polyfills', () => {
+                const polyfills2 = state.fs.readFileSync('/polyfills-1.js', 'utf-8');
+                expect(state.polyfillsFile).to.not.contain(`'Promise' in this`);
+                expect(polyfills2).to.not.contain(`'find' in Array.prototype`);
+            });
+
+            it('executes the "app" entry module correctly', () => {
+                expect(state.window).to.have.property('Promise');
+                expect(state.window.Array.prototype).to.not.have.property('find');
+                expect(state.dom.serialize())
+                    .to.contain('<p>---SUCCESS---</p><p>[entry2]function[/entry2]</p>')
+                    .and.to.not.contain('entry3');
+            });
 
-        it('executes the "app" entry module correctly', () => {
-            expect(state.window).to.have.property('Promise');
-            expect(state.window.Array.prototype).to.not.have.property('find');
-            expect(state.dom.serialize())
-                .to.contain('<p>---SUCCESS---</p><p>[entry2]function[/entry2]</p>')
-                .and.to.not.contain('entry3');
+            it('executes the "other" entry module correctly', () => {
+                const dom = createDOM();
+                dom.window.eval('delete window.Promise');
+                dom.window.eval('delete window.Array.prototype.find');
+                dom.window.eval(state.fs.readFileSync('/other.js', 'utf-8'));
+                executeScript(dom, state.fs);
+                expect(dom.window).to.not.have.property('Promise');
+                expect(dom.window.Array.prototype).to.have.property('find');
+                expect(dom.serialize())
+                    .to.contain('<p>[entry3]function[/entry3]</p>')
+                    .and.to.not.contain('---SUCCESS---')
+                    .and.to.not.contain('entry2');
+            });
         });
 
-        it('executes the "other" entry module correctly', () => {
-            const dom = createDOM();
-            dom.window.eval('delete window.Promise');
-            dom.window.eval('delete window.Array.prototype.find');
-            dom.window.eval(state.fs.readFileSync('/other.js', 'utf-8'));
-            executeScript(dom, state.fs);
-            expect(dom.window).to.not.have.property('Promise');
-            expect(dom.window.Array.prototype).to.have.property('find');
-            expect(dom.serialize())
-                .to.contain('<p>[entry3]function[/entry3]</p>')
-                .and.to.not.contain('---SUCCESS---')
-                .and.to.not.contain('entry2');
+        describe('with the same polyfills', () => {
+            it('creates five assets: app.js, other.js, polyfills.01.js, polyfills.10.js, polyfills.11.js', async () => {
+                const state = await test({
+                    entry: {
+                        app: `webpack-polyfill-injector?${JSON.stringify({
+                            modules: [
+                                './test/fixtures/entry.js',
+                                './test/fixtures/entry2.js',
+                            ],
+                            polyfills: ['Promise', 'Array.prototype.find'],
+                        })}!`,
+                        other: `webpack-polyfill-injector?${JSON.stringify({
+                            modules: [
+                                './test/fixtures/entry3.js',
+                            ],
+                            polyfills: ['Promise', 'Array.prototype.find'],
+                        })}!`,
+                    },
+                    plugins: [new PolyfillInjectorPlugin()],
+                });
+                const assets = state.stats.compilation.assets;
+                expect(Object.keys(assets)).to.have.lengthOf(5);
+                expect(assets).to.have.property('app.js');
+                expect(assets).to.have.property('polyfills.01.js');
+                expect(assets).to.have.property('polyfills.10.js');
+                expect(assets).to.have.property('polyfills.11.js');
+                expect(assets).to.have.property('other.js');
+            });
         });
     });
 
 
     describe('When using [hash] as part of the filename', () => {
-        let state; // eslint-disable-line init-declarations
-        before(async () => {
-            state = await compile({
+        it('creates hashed polyfills files', async () => {
+            const state = await compile({
                 output: {filename: '[name].[hash].js'},
                 entry: {app: 'webpack-polyfill-injector?{modules:["./test/fixtures/entry.js"]}!'},
                 plugins: [new PolyfillInjectorPlugin({polyfills: ['Promise', 'Array.prototype.find']})],
             });
-        });
 
-        it('creates hashed polyfills files', () => {
             const polyfillFiles = state.fs.readdirSync('/').filter(name => name.startsWith('polyfills'));
             expect(polyfillFiles).to.have.lengthOf(3);
             const hash = polyfillFiles[0].replace(/^polyfills\.(.*)\.[01][01]\.js$/, '$1');
@@ -403,16 +432,13 @@ describe('webpack-polyfill-injector', () => {
 
 
     describe('When using [chunkhash] as part of the filename', () => {
-        let state; // eslint-disable-line init-declarations
-        before(async () => {
-            state = await compile({
+        it('creates hashed polyfills files', async () => {
+            const state = await compile({
                 output: {filename: '[name].[chunkhash:7].js'},
                 entry: {app: 'webpack-polyfill-injector?{modules:["./test/fixtures/entry.js"]}!'},
                 plugins: [new PolyfillInjectorPlugin({polyfills: ['Promise', 'Array.prototype.find']})],
             });
-        });
 
-        it('creates hashed polyfills files', () => {
             const polyfillFiles = state.fs.readdirSync('/').filter(name => name.startsWith('polyfills'));
             expect(polyfillFiles).to.have.lengthOf(3);
             const hash = polyfillFiles[0].replace(/^polyfills\.(.*)\.[01][01]\.js$/, '$1');
@@ -427,6 +453,16 @@ describe('webpack-polyfill-injector', () => {
     });
 
 
+    describe('When configuring strings instead of arrays', () => {
+        it('interprets them as arrays', () => {
+            expect(compile({
+                entry: {app: 'webpack-polyfill-injector?{modules:"./test/fixtures/entry.js"}!'},
+                plugins: [new PolyfillInjectorPlugin({polyfills: 'Promise'})],
+            })).to.be.fulfilled();
+        });
+    });
+
+
     describe('When using an illegal configuration', () => {
         describe('Plugin without loader', () => {
             it('yields a useful error message', () =>