diff --git a/src/index.js b/src/index.js
index b3e565ec..4c904b79 100644
--- a/src/index.js
+++ b/src/index.js
@@ -60,8 +60,9 @@ module.exports = (options = {}) => {
       }
 
       // Rollup >= 0.48 replace `sourceMap` with `sourcemap`.
-      if (opts.sourceMap || opts.sourcemap) {
-        plugin.enableSourceMap();
+      // If `sourcemap` is disabled globally, disable it on the plugin.
+      if (opts.sourceMap === false || opts.sourcemap === false) {
+        plugin.disableSourceMap();
       }
     },
 
diff --git a/src/license-plugin.js b/src/license-plugin.js
index 99c52332..0c20d8a6 100644
--- a/src/license-plugin.js
+++ b/src/license-plugin.js
@@ -48,7 +48,7 @@ class LicensePlugin {
     this.name = 'rollup-plugin-license';
 
     this._options = options;
-    this._sourceMap = false;
+    this._sourceMap = true;
     this._cwd = process.cwd();
     this._dependencies = {};
     this._pkg = require(path.join(this._cwd, 'package.json'));
@@ -65,8 +65,8 @@ class LicensePlugin {
    *
    * @return {void}
    */
-  enableSourceMap() {
-    this._sourceMap = true;
+  disableSourceMap() {
+    this._sourceMap = false;
   }
 
   /**
diff --git a/test/index.spec.js b/test/index.spec.js
index 9a464d21..73a2a949 100644
--- a/test/index.spec.js
+++ b/test/index.spec.js
@@ -45,7 +45,7 @@ describe('rollup-plugin-license', () => {
   });
 
   it('should enable sourceMap if options.sourceMap is true', () => {
-    spyOn(LicensePlugin.prototype, 'enableSourceMap').and.callThrough();
+    spyOn(LicensePlugin.prototype, 'disableSourceMap').and.callThrough();
 
     const instance = plugin();
     const result = instance.options({
@@ -53,11 +53,11 @@ describe('rollup-plugin-license', () => {
     });
 
     expect(result).not.toBeDefined();
-    expect(LicensePlugin.prototype.enableSourceMap).toHaveBeenCalledWith();
+    expect(LicensePlugin.prototype.disableSourceMap).not.toHaveBeenCalled();
   });
 
   it('should enable sourceMap if options.sourcemap (lowercase) is true', () => {
-    spyOn(LicensePlugin.prototype, 'enableSourceMap').and.callThrough();
+    spyOn(LicensePlugin.prototype, 'disableSourceMap').and.callThrough();
 
     const instance = plugin();
     const result = instance.options({
@@ -65,11 +65,11 @@ describe('rollup-plugin-license', () => {
     });
 
     expect(result).not.toBeDefined();
-    expect(LicensePlugin.prototype.enableSourceMap).toHaveBeenCalledWith();
+    expect(LicensePlugin.prototype.disableSourceMap).not.toHaveBeenCalled();
   });
 
   it('should not enable sourceMap if options.sourceMap is false', () => {
-    spyOn(LicensePlugin.prototype, 'enableSourceMap').and.callThrough();
+    spyOn(LicensePlugin.prototype, 'disableSourceMap').and.callThrough();
 
     const instance = plugin();
     const result = instance.options({
@@ -77,27 +77,39 @@ describe('rollup-plugin-license', () => {
     });
 
     expect(result).not.toBeDefined();
-    expect(LicensePlugin.prototype.enableSourceMap).not.toHaveBeenCalled();
+    expect(LicensePlugin.prototype.disableSourceMap).toHaveBeenCalledWith();
   });
 
-  it('should not enable sourceMap by default', () => {
-    spyOn(LicensePlugin.prototype, 'enableSourceMap').and.callThrough();
+  it('should not enable sourceMap if options.sourcemap (lowercase) is false', () => {
+    spyOn(LicensePlugin.prototype, 'disableSourceMap').and.callThrough();
+
+    const instance = plugin();
+    const result = instance.options({
+      sourcemap: false,
+    });
+
+    expect(result).not.toBeDefined();
+    expect(LicensePlugin.prototype.disableSourceMap).toHaveBeenCalledWith();
+  });
+
+  it('should enable sourceMap by default', () => {
+    spyOn(LicensePlugin.prototype, 'disableSourceMap').and.callThrough();
 
     const instance = plugin();
     const result = instance.options({});
 
     expect(result).not.toBeDefined();
-    expect(LicensePlugin.prototype.enableSourceMap).not.toHaveBeenCalled();
+    expect(LicensePlugin.prototype.disableSourceMap).not.toHaveBeenCalled();
   });
 
-  it('should not enable sourceMap if options is not set', () => {
-    spyOn(LicensePlugin.prototype, 'enableSourceMap').and.callThrough();
+  it('should enable sourceMap if options is not set', () => {
+    spyOn(LicensePlugin.prototype, 'disableSourceMap').and.callThrough();
 
     const instance = plugin();
     const result = instance.options();
 
     expect(result).not.toBeDefined();
-    expect(LicensePlugin.prototype.enableSourceMap).not.toHaveBeenCalled();
+    expect(LicensePlugin.prototype.disableSourceMap).not.toHaveBeenCalled();
   });
 
   it('should prepend banner when bundle is transformed', () => {
diff --git a/test/license-plugin.spec.js b/test/license-plugin.spec.js
index fa4b882d..cb6e35e9 100644
--- a/test/license-plugin.spec.js
+++ b/test/license-plugin.spec.js
@@ -42,16 +42,16 @@ describe('LicensePlugin', () => {
     const plugin = new LicensePlugin();
     expect(plugin._cwd).toBeDefined();
     expect(plugin._pkg).toBeDefined();
-    expect(plugin._sourceMap).toBe(false);
+    expect(plugin._sourceMap).toBe(true);
     expect(plugin._dependencies).toEqual({});
   });
 
-  it('should enable source map', () => {
+  it('should disable source map', () => {
     const plugin = new LicensePlugin();
-    expect(plugin._sourceMap).toBe(false);
-
-    plugin.enableSourceMap();
     expect(plugin._sourceMap).toBe(true);
+
+    plugin.disableSourceMap();
+    expect(plugin._sourceMap).toBe(false);
   });
 
   it('should load pkg', () => {
@@ -341,7 +341,7 @@ describe('LicensePlugin', () => {
     const result = instance.prependBanner(code);
 
     expect(result).toBeDefined();
-    expect(result.map).not.toBeDefined();
+    expect(result.map).toBeDefined();
     expect(result.code).toEqual(
       `/**\n` +
       ` * Test banner.\n` +
@@ -365,7 +365,7 @@ describe('LicensePlugin', () => {
     const result = instance.prependBanner(code);
 
     expect(result).toBeDefined();
-    expect(result.map).not.toBeDefined();
+    expect(result.map).toBeDefined();
     expect(result.code).toEqual(
       `/**\n` +
       ` * Test banner.\n` +
@@ -394,7 +394,7 @@ describe('LicensePlugin', () => {
 
     expect(fs.readFileSync).toHaveBeenCalledWith(jasmine.any(String), encoding);
     expect(result).toBeDefined();
-    expect(result.map).not.toBeDefined();
+    expect(result.map).toBeDefined();
     expect(result.code).toEqual(
       `/**\n` +
       ` * Test banner.\n` +
@@ -406,20 +406,20 @@ describe('LicensePlugin', () => {
     );
   });
 
-  it('should prepend banner to bundle with source map', () => {
+  it('should prepend banner to bundle without source map', () => {
     const instance = new LicensePlugin({
       banner: {
         file: path.join(__dirname, 'fixtures', 'banner.js'),
       },
     });
 
-    instance.enableSourceMap();
+    instance.disableSourceMap();
 
     const code = 'var foo = 0;';
     const result = instance.prependBanner(code);
 
     expect(result).toBeDefined();
-    expect(result.map).toBeDefined();
+    expect(result.map).not.toBeDefined();
     expect(result.code).toEqual(
       `/**\n` +
       ` * Test banner.\n` +
@@ -433,7 +433,6 @@ describe('LicensePlugin', () => {
 
   it('should not prepend default banner to bundle', () => {
     const instance = new LicensePlugin();
-    instance.enableSourceMap();
 
     const code = 'var foo = 0;';
     const result = instance.prependBanner(code);
@@ -451,8 +450,6 @@ describe('LicensePlugin', () => {
       },
     });
 
-    instance.enableSourceMap();
-
     const code = 'var foo = 0;';
     const result = instance.prependBanner(code);
 
@@ -492,8 +489,6 @@ describe('LicensePlugin', () => {
       },
     });
 
-    instance.enableSourceMap();
-
     const code = 'var foo = 0;';
     const result = instance.prependBanner(code);