diff --git a/packages/babel-core/test/parse.js b/packages/babel-core/test/parse.js
index ed5c95b4f3..ec36951cb0 100644
--- a/packages/babel-core/test/parse.js
+++ b/packages/babel-core/test/parse.js
@@ -23,7 +23,9 @@ describe("parse", function() {
     const output = require(fixture("output.json"));
 
     const result = parse(input, {
-      parserOpts: { plugins: ["decorators"] },
+      parserOpts: {
+        plugins: [["decorators", { decoratorsBeforeExport: false }]],
+      },
       cwd: fixture(),
     });
     expect(JSON.parse(JSON.stringify(result))).toEqual(output);
diff --git a/packages/babel-parser/src/plugin-utils.js b/packages/babel-parser/src/plugin-utils.js
index 69cc39f7ac..8260bdc00c 100644
--- a/packages/babel-parser/src/plugin-utils.js
+++ b/packages/babel-parser/src/plugin-utils.js
@@ -41,13 +41,26 @@ export function getPluginOption(
 const PIPELINE_PROPOSALS = ["minimal"];
 
 export function validatePlugins(plugins: PluginList) {
-  if (
-    hasPlugin(plugins, "decorators") &&
-    hasPlugin(plugins, "decorators-legacy")
-  ) {
-    throw new Error(
-      "Cannot use the decorators and decorators-legacy plugin together",
+  if (hasPlugin(plugins, "decorators")) {
+    if (hasPlugin(plugins, "decorators-legacy")) {
+      throw new Error(
+        "Cannot use the decorators and decorators-legacy plugin together",
+      );
+    }
+
+    const decoratorsBeforeExport = getPluginOption(
+      plugins,
+      "decorators",
+      "decoratorsBeforeExport",
     );
+    if (decoratorsBeforeExport == null) {
+      throw new Error(
+        "The 'decorators' plugin requires a" +
+          " 'decoratorsBeforeExport' option, whose value must be a boolean.",
+      );
+    } else if (typeof decoratorsBeforeExport !== "boolean") {
+      throw new Error("'decoratorsBeforeExport' must be a boolean.");
+    }
   }
 
   if (hasPlugin(plugins, "flow") && hasPlugin(plugins, "typescript")) {
diff --git a/packages/babel-parser/test/fixtures/experimental/decorators-2/class-property/options.json b/packages/babel-parser/test/fixtures/experimental/decorators-2/class-property/options.json
index 806b2fc7ca..21fa2f7d9b 100644
--- a/packages/babel-parser/test/fixtures/experimental/decorators-2/class-property/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/decorators-2/class-property/options.json
@@ -1,3 +1,7 @@
 {
-  "plugins": ["classProperties", "classPrivateProperties", "decorators"]
+  "plugins": [
+    "classProperties",
+    "classPrivateProperties",
+    ["decorators", { "decoratorsBeforeExport": false }]
+  ]
 }
diff --git a/packages/babel-parser/test/fixtures/experimental/decorators-2/compued-property/options.json b/packages/babel-parser/test/fixtures/experimental/decorators-2/compued-property/options.json
index 49038f416f..1ec7ff9a42 100644
--- a/packages/babel-parser/test/fixtures/experimental/decorators-2/compued-property/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/decorators-2/compued-property/options.json
@@ -1,3 +1,6 @@
 {
-  "plugins": ["decorators", "classProperties"]
+  "plugins": [
+    ["decorators", { "decoratorsBeforeExport": false }],
+    "classProperties"
+  ]
 }
diff --git a/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-boolean/input.js b/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-boolean/input.js
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-boolean/options.json b/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-boolean/options.json
new file mode 100644
index 0000000000..30762d985c
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-boolean/options.json
@@ -0,0 +1,6 @@
+{
+  "plugins": [
+    ["decorators", { "decoratorsBeforeExport": "yes" }]
+  ],
+  "throws": "'decoratorsBeforeExport' must be a boolean."
+}
diff --git a/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-required/input.js b/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-required/input.js
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-required/options.json b/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-required/options.json
new file mode 100644
index 0000000000..6e76b5fb33
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/experimental/decorators-2/decoratorsBeforeExport-required/options.json
@@ -0,0 +1,4 @@
+{
+  "plugins": ["decorators"],
+  "throws": "The 'decorators' plugin requires a 'decoratorsBeforeExport' option, whose value must be a boolean."
+}
diff --git a/packages/babel-parser/test/fixtures/experimental/decorators-2/options.json b/packages/babel-parser/test/fixtures/experimental/decorators-2/options.json
index d760b0afda..14ae2b56d3 100644
--- a/packages/babel-parser/test/fixtures/experimental/decorators-2/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/decorators-2/options.json
@@ -1,3 +1,5 @@
 {
-  "plugins": ["decorators"]
+  "plugins": [
+    ["decorators", { "decoratorsBeforeExport": false }]
+  ]
 }
diff --git a/packages/babel-parser/test/fixtures/experimental/decorators-2/private-property/options.json b/packages/babel-parser/test/fixtures/experimental/decorators-2/private-property/options.json
index 806b2fc7ca..21fa2f7d9b 100644
--- a/packages/babel-parser/test/fixtures/experimental/decorators-2/private-property/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/decorators-2/private-property/options.json
@@ -1,3 +1,7 @@
 {
-  "plugins": ["classProperties", "classPrivateProperties", "decorators"]
+  "plugins": [
+    "classProperties",
+    "classPrivateProperties",
+    ["decorators", { "decoratorsBeforeExport": false }]
+  ]
 }
diff --git a/packages/babel-parser/test/fixtures/experimental/decorators-2/static-property/options.json b/packages/babel-parser/test/fixtures/experimental/decorators-2/static-property/options.json
index b508cf45fd..4ee4c94460 100644
--- a/packages/babel-parser/test/fixtures/experimental/decorators-2/static-property/options.json
+++ b/packages/babel-parser/test/fixtures/experimental/decorators-2/static-property/options.json
@@ -1,3 +1,6 @@
 {
-  "plugins": ["classProperties", "decorators"]
+  "plugins": [
+    "classProperties",
+    ["decorators", { "decoratorsBeforeExport": false }]
+  ]
 }
diff --git a/packages/babel-parser/test/plugin-options.js b/packages/babel-parser/test/plugin-options.js
index a2f29026b6..44e6cb26ae 100644
--- a/packages/babel-parser/test/plugin-options.js
+++ b/packages/babel-parser/test/plugin-options.js
@@ -9,19 +9,56 @@ describe("plugin options", function() {
     // NOTE: This test is not specific about decorators, it can be applied
     // to any plugin with options.
 
-    const NAME = "decorators";
-    const OPT_1 = [NAME, { decoratorsBeforeExport: true }];
-    const OPT_2 = [NAME, { decoratorsBeforeExport: false }];
-    const SYNTAX_1 = "@dec export class C {}";
-    const SYNTAX_2 = "export @dec class C {}";
-    const SYNTAX_DEFAULT = "export @dec class C {}";
-
     it("when they aren't specified", function() {
-      expect(getParser(SYNTAX_DEFAULT, [NAME, OPT_1])).not.toThrow();
-      expect(getParser(SYNTAX_DEFAULT, [NAME, OPT_2])).not.toThrow();
+      const WITHOUT_FLAG = "flow";
+      const WITH_FLAG = ["flow", { all: true }];
+
+      const CODE = "new Foo<x>(y)";
+
+      const AST_WITHOUT_FLAG = {
+        type: "BinaryExpression",
+        operator: ">",
+        left: {
+          type: "BinaryExpression",
+          operator: "<",
+          left: { type: "NewExpression" },
+          right: { type: "Identifier" },
+        },
+        right: { type: "Identifier", extra: { parenthesized: true } },
+      };
+
+      const AST_WITH_FLAG = {
+        type: "NewExpression",
+        callee: { type: "Identifier" },
+        arguments: [{ type: "Identifier" }],
+        typeArguments: {
+          type: "TypeParameterInstantiation",
+          params: [
+            { type: "GenericTypeAnnotation", id: { type: "Identifier" } },
+          ],
+        },
+      };
+
+      expect(
+        getParser(CODE, [WITHOUT_FLAG, WITH_FLAG])().program.body[0].expression,
+      ).toMatchObject(AST_WITHOUT_FLAG);
+
+      expect(
+        getParser(CODE, [WITHOUT_FLAG])().program.body[0].expression,
+      ).toMatchObject(AST_WITHOUT_FLAG);
+
+      expect(
+        getParser(CODE, [WITH_FLAG])().program.body[0].expression,
+      ).toMatchObject(AST_WITH_FLAG);
     });
 
     it("when they are specified", function() {
+      const NAME = "decorators";
+      const OPT_1 = [NAME, { decoratorsBeforeExport: true }];
+      const OPT_2 = [NAME, { decoratorsBeforeExport: false }];
+      const SYNTAX_1 = "@dec export class C {}";
+      const SYNTAX_2 = "export @dec class C {}";
+
       expect(getParser(SYNTAX_1, [OPT_1, OPT_2])).not.toThrow();
       expect(getParser(SYNTAX_2, [OPT_2, OPT_1])).not.toThrow();
       expect(getParser(SYNTAX_1, [OPT_2, OPT_1])).toThrow();
diff --git a/packages/babel-plugin-syntax-decorators/src/index.js b/packages/babel-plugin-syntax-decorators/src/index.js
index 7c2a454c94..1a73a63c88 100644
--- a/packages/babel-plugin-syntax-decorators/src/index.js
+++ b/packages/babel-plugin-syntax-decorators/src/index.js
@@ -17,7 +17,14 @@ export default declare((api, options) => {
   }
 
   const { decoratorsBeforeExport } = options;
-  if (decoratorsBeforeExport !== undefined) {
+  if (decoratorsBeforeExport === undefined) {
+    if (!legacy) {
+      throw new Error(
+        "The '@babel/plugin-syntax-decorators' plugin requires a" +
+          " 'decoratorsBeforeExport' option, whose value must be a boolean.",
+      );
+    }
+  } else {
     if (legacy) {
       throw new Error(
         "'decoratorsBeforeExport' can't be used with legacy decorators.",
diff --git a/packages/babel-plugin-syntax-decorators/test/index.js b/packages/babel-plugin-syntax-decorators/test/index.js
index 4ff1679172..38106f6288 100644
--- a/packages/babel-plugin-syntax-decorators/test/index.js
+++ b/packages/babel-plugin-syntax-decorators/test/index.js
@@ -37,6 +37,10 @@ describe("'decoratorsBeforeExport' option", function() {
     expect(makeParser("", { decoratorsBeforeExport: "before" })).toThrow();
   });
 
+  test.skip("is required", function() {
+    expect(makeParser("", { legacy: false })).toThrow(/decoratorsBeforeExport/);
+  });
+
   test("is incompatible with legacy", function() {
     expect(
       makeParser("", { decoratorsBeforeExport: false, legacy: true }),
@@ -47,8 +51,6 @@ describe("'decoratorsBeforeExport' option", function() {
   const AFTER = "export @dec class Foo {}";
 
   // These are skipped
-  run(BEFORE, undefined, true);
-  run(AFTER, undefined, false);
   run(BEFORE, true, false);
   run(AFTER, true, true);
   run(BEFORE, false, true);