diff --git a/packages/babel-parser/src/parser/expression.js b/packages/babel-parser/src/parser/expression.js
index 5fd5c402efc9..7eae9fff270f 100644
--- a/packages/babel-parser/src/parser/expression.js
+++ b/packages/babel-parser/src/parser/expression.js
@@ -490,11 +490,7 @@ export default class ExpressionParser extends LValParser {
   // Parse unary operators, both prefix and postfix.
 
   parseMaybeUnary(refShorthandDefaultPos: ?Pos): N.Expression {
-    if (
-      this.isContextual("await") &&
-      (this.scope.inAsync ||
-        (!this.scope.inFunction && this.options.allowAwaitOutsideFunction))
-    ) {
+    if (this.isContextual("await") && this.isAwaitAllowed()) {
       return this.parseAwait();
     } else if (this.state.type.prefix) {
       const node = this.startNode();
@@ -676,8 +672,8 @@ export default class ExpressionParser extends LValParser {
       const oldYieldPos = this.state.yieldPos;
       const oldAwaitPos = this.state.awaitPos;
       this.state.maybeInArrowParameters = true;
-      this.state.yieldPos = 0;
-      this.state.awaitPos = 0;
+      this.state.yieldPos = -1;
+      this.state.awaitPos = -1;
 
       this.next();
 
@@ -716,8 +712,34 @@ export default class ExpressionParser extends LValParser {
 
         // We keep the old value if it isn't null, for cases like
         //   (x = async(yield)) => {}
-        this.state.yieldPos = oldYieldPos || this.state.yieldPos;
-        this.state.awaitPos = oldAwaitPos || this.state.awaitPos;
+        //
+        // Hi developer of the future :) If you are implementing generator
+        // arrow functions, please read the note below about "await" and
+        // verify if the same logic is needed for yield.
+        if (oldYieldPos !== -1) this.state.yieldPos = oldYieldPos;
+
+        // Await is trickier than yield. When parsing a possible arrow function
+        // (e.g. something starting with `async(`) we don't know if its possible
+        // parameters will actually be inside an async arrow function or if it is
+        // a normal call expression.
+        // If it ended up being a call expression, if we are in a context where
+        // await expression are disallowed (and thus "await" is an identifier)
+        // we must be careful not to leak this.state.awaitPos to an even outer
+        // context, where "await" could not be an identifier.
+        // For example, this code is valid because "await" isn't directly inside
+        // an async function:
+        //
+        //     async function a() {
+        //       function b(param = async (await)) {
+        //       }
+        //     }
+        //
+        if (
+          (!this.isAwaitAllowed() && !oldMaybeInArrowParameters) ||
+          oldAwaitPos !== -1
+        ) {
+          this.state.awaitPos = oldAwaitPos;
+        }
       }
 
       this.state.maybeInArrowParameters = oldMaybeInArrowParameters;
@@ -1231,8 +1253,8 @@ export default class ExpressionParser extends LValParser {
     const oldAwaitPos = this.state.awaitPos;
     const oldInFSharpPipelineDirectBody = this.state.inFSharpPipelineDirectBody;
     this.state.maybeInArrowParameters = true;
-    this.state.yieldPos = 0;
-    this.state.awaitPos = 0;
+    this.state.yieldPos = -1;
+    this.state.awaitPos = -1;
     this.state.inFSharpPipelineDirectBody = false;
 
     const innerStartPos = this.state.start;
@@ -1310,8 +1332,8 @@ export default class ExpressionParser extends LValParser {
 
     // We keep the old value if it isn't null, for cases like
     //   (x = (yield)) => {}
-    this.state.yieldPos = oldYieldPos || this.state.yieldPos;
-    this.state.awaitPos = oldAwaitPos || this.state.awaitPos;
+    if (oldYieldPos !== -1) this.state.yieldPos = oldYieldPos;
+    if (oldAwaitPos !== -1) this.state.awaitPos = oldAwaitPos;
 
     if (!exprList.length) {
       this.unexpected(this.state.lastTokStart);
@@ -1804,8 +1826,8 @@ export default class ExpressionParser extends LValParser {
   ): T {
     const oldYieldPos = this.state.yieldPos;
     const oldAwaitPos = this.state.awaitPos;
-    this.state.yieldPos = 0;
-    this.state.awaitPos = 0;
+    this.state.yieldPos = -1;
+    this.state.awaitPos = -1;
 
     this.initFunction(node, isAsync);
     node.generator = !!isGenerator;
@@ -1842,8 +1864,8 @@ export default class ExpressionParser extends LValParser {
     const oldYieldPos = this.state.yieldPos;
     const oldAwaitPos = this.state.awaitPos;
     this.state.maybeInArrowParameters = false;
-    this.state.yieldPos = 0;
-    this.state.awaitPos = 0;
+    this.state.yieldPos = -1;
+    this.state.awaitPos = -1;
 
     if (params) this.setArrowFunctionParameters(node, params);
     this.parseFunctionBody(node, true);
@@ -2117,11 +2139,18 @@ export default class ExpressionParser extends LValParser {
       );
     }
 
-    if (this.scope.inAsync && word === "await") {
-      this.raise(
-        startLoc,
-        "Can not use 'await' as identifier inside an async function",
-      );
+    if (word === "await") {
+      if (this.scope.inAsync) {
+        this.raise(
+          startLoc,
+          "Can not use 'await' as identifier inside an async function",
+        );
+      } else if (
+        this.state.awaitPos === -1 &&
+        (this.state.maybeInArrowParameters || this.isAwaitAllowed())
+      ) {
+        this.state.awaitPos = this.state.start;
+      }
     }
 
     if (this.state.inClassProperty && word === "arguments") {
@@ -2151,10 +2180,16 @@ export default class ExpressionParser extends LValParser {
     }
   }
 
+  isAwaitAllowed(): boolean {
+    if (this.scope.inFunction) return this.scope.inAsync;
+    if (this.options.allowAwaitOutsideFunction) return true;
+    return false;
+  }
+
   // Parses await expression inside async function.
 
   parseAwait(): N.AwaitExpression {
-    if (!this.state.awaitPos) {
+    if (this.state.awaitPos === -1) {
       this.state.awaitPos = this.state.start;
     }
     const node = this.startNode();
@@ -2183,7 +2218,7 @@ export default class ExpressionParser extends LValParser {
   // Parses yield expression inside generator.
 
   parseYield(noIn?: ?boolean): N.YieldExpression {
-    if (!this.state.yieldPos) {
+    if (this.state.yieldPos === -1) {
       this.state.yieldPos = this.state.start;
     }
     const node = this.startNode();
diff --git a/packages/babel-parser/src/parser/statement.js b/packages/babel-parser/src/parser/statement.js
index bb5702e7de34..bfadb601dbcf 100644
--- a/packages/babel-parser/src/parser/statement.js
+++ b/packages/babel-parser/src/parser/statement.js
@@ -1050,12 +1050,14 @@ export default class StatementParser extends ExpressionParser {
       node.id = this.parseFunctionId(requireId);
     }
 
+    const oldMaybeInArrowParameters = this.state.maybeInArrowParameters;
     const oldInClassProperty = this.state.inClassProperty;
     const oldYieldPos = this.state.yieldPos;
     const oldAwaitPos = this.state.awaitPos;
+    this.state.maybeInArrowParameters = false;
     this.state.inClassProperty = false;
-    this.state.yieldPos = 0;
-    this.state.awaitPos = 0;
+    this.state.yieldPos = -1;
+    this.state.awaitPos = -1;
     this.scope.enter(functionFlags(node.async, node.generator));
 
     if (!isStatement) {
@@ -1084,6 +1086,7 @@ export default class StatementParser extends ExpressionParser {
       this.checkFunctionStatementId(node);
     }
 
+    this.state.maybeInArrowParameters = oldMaybeInArrowParameters;
     this.state.inClassProperty = oldInClassProperty;
     this.state.yieldPos = oldYieldPos;
     this.state.awaitPos = oldAwaitPos;
diff --git a/packages/babel-parser/src/parser/util.js b/packages/babel-parser/src/parser/util.js
index bd6139a2480a..41e19c1a3c2e 100644
--- a/packages/babel-parser/src/parser/util.js
+++ b/packages/babel-parser/src/parser/util.js
@@ -159,15 +159,15 @@ export default class UtilParser extends Tokenizer {
 
   checkYieldAwaitInDefaultParams() {
     if (
-      this.state.yieldPos &&
-      (!this.state.awaitPos || this.state.yieldPos < this.state.awaitPos)
+      this.state.yieldPos !== -1 &&
+      (this.state.awaitPos === -1 || this.state.yieldPos < this.state.awaitPos)
     ) {
       this.raise(
         this.state.yieldPos,
         "Yield cannot be used as name inside a generator function",
       );
     }
-    if (this.state.awaitPos) {
+    if (this.state.awaitPos !== -1) {
       this.raise(
         this.state.awaitPos,
         "Await cannot be used as name inside an async function",
diff --git a/packages/babel-parser/src/tokenizer/state.js b/packages/babel-parser/src/tokenizer/state.js
index 80842fbc5103..a9dccb2bf0e6 100644
--- a/packages/babel-parser/src/tokenizer/state.js
+++ b/packages/babel-parser/src/tokenizer/state.js
@@ -97,8 +97,8 @@ export default class State {
   decoratorStack: Array<Array<N.Decorator>> = [[]];
 
   // Positions to delayed-check that yield/await does not exist in default parameters.
-  yieldPos: number = 0;
-  awaitPos: number = 0;
+  yieldPos: number = -1;
+  awaitPos: number = -1;
 
   // Token store.
   tokens: Array<Token | N.Comment> = [];
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-binding-inside-arrow-params-inside-async-arrow-params/input.js b/packages/babel-parser/test/fixtures/es2017/async-functions/await-binding-inside-arrow-params-inside-async-arrow-params/input.js
new file mode 100644
index 000000000000..5b6e6b2866ae
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-binding-inside-arrow-params-inside-async-arrow-params/input.js
@@ -0,0 +1 @@
+async (a = ({ await }) => {}) => {};
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-binding-inside-arrow-params-inside-async-arrow-params/options.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-binding-inside-arrow-params-inside-async-arrow-params/options.json
new file mode 100644
index 000000000000..c066100759e2
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-binding-inside-arrow-params-inside-async-arrow-params/options.json
@@ -0,0 +1,3 @@
+{
+  "throws": "Await cannot be used as name inside an async function (1:20)"
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-async-call-inside-parameters-of-function-inside-async-function/input.js b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-async-call-inside-parameters-of-function-inside-async-function/input.js
new file mode 100644
index 000000000000..1c99cb921526
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-async-call-inside-parameters-of-function-inside-async-function/input.js
@@ -0,0 +1,3 @@
+async function f() {
+  function g(x = async(await)) {}
+}
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-async-call-inside-parameters-of-function-inside-async-function/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-async-call-inside-parameters-of-function-inside-async-function/output.json
new file mode 100644
index 000000000000..41946b0a2bcb
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-inside-async-call-inside-parameters-of-function-inside-async-function/output.json
@@ -0,0 +1,224 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 56,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 3,
+      "column": 1
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 56,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 3,
+        "column": 1
+      }
+    },
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start": 0,
+        "end": 56,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 3,
+            "column": 1
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 15,
+          "end": 16,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 15
+            },
+            "end": {
+              "line": 1,
+              "column": 16
+            },
+            "identifierName": "f"
+          },
+          "name": "f"
+        },
+        "generator": false,
+        "async": true,
+        "params": [],
+        "body": {
+          "type": "BlockStatement",
+          "start": 19,
+          "end": 56,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 19
+            },
+            "end": {
+              "line": 3,
+              "column": 1
+            }
+          },
+          "body": [
+            {
+              "type": "FunctionDeclaration",
+              "start": 23,
+              "end": 54,
+              "loc": {
+                "start": {
+                  "line": 2,
+                  "column": 2
+                },
+                "end": {
+                  "line": 2,
+                  "column": 33
+                }
+              },
+              "id": {
+                "type": "Identifier",
+                "start": 32,
+                "end": 33,
+                "loc": {
+                  "start": {
+                    "line": 2,
+                    "column": 11
+                  },
+                  "end": {
+                    "line": 2,
+                    "column": 12
+                  },
+                  "identifierName": "g"
+                },
+                "name": "g"
+              },
+              "generator": false,
+              "async": false,
+              "params": [
+                {
+                  "type": "AssignmentPattern",
+                  "start": 34,
+                  "end": 50,
+                  "loc": {
+                    "start": {
+                      "line": 2,
+                      "column": 13
+                    },
+                    "end": {
+                      "line": 2,
+                      "column": 29
+                    }
+                  },
+                  "left": {
+                    "type": "Identifier",
+                    "start": 34,
+                    "end": 35,
+                    "loc": {
+                      "start": {
+                        "line": 2,
+                        "column": 13
+                      },
+                      "end": {
+                        "line": 2,
+                        "column": 14
+                      },
+                      "identifierName": "x"
+                    },
+                    "name": "x"
+                  },
+                  "right": {
+                    "type": "CallExpression",
+                    "start": 38,
+                    "end": 50,
+                    "loc": {
+                      "start": {
+                        "line": 2,
+                        "column": 17
+                      },
+                      "end": {
+                        "line": 2,
+                        "column": 29
+                      }
+                    },
+                    "callee": {
+                      "type": "Identifier",
+                      "start": 38,
+                      "end": 43,
+                      "loc": {
+                        "start": {
+                          "line": 2,
+                          "column": 17
+                        },
+                        "end": {
+                          "line": 2,
+                          "column": 22
+                        },
+                        "identifierName": "async"
+                      },
+                      "name": "async"
+                    },
+                    "arguments": [
+                      {
+                        "type": "Identifier",
+                        "start": 44,
+                        "end": 49,
+                        "loc": {
+                          "start": {
+                            "line": 2,
+                            "column": 23
+                          },
+                          "end": {
+                            "line": 2,
+                            "column": 28
+                          },
+                          "identifierName": "await"
+                        },
+                        "name": "await"
+                      }
+                    ]
+                  }
+                }
+              ],
+              "body": {
+                "type": "BlockStatement",
+                "start": 52,
+                "end": 54,
+                "loc": {
+                  "start": {
+                    "line": 2,
+                    "column": 31
+                  },
+                  "end": {
+                    "line": 2,
+                    "column": 33
+                  }
+                },
+                "body": [],
+                "directives": []
+              }
+            }
+          ],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-object-key-inside-arrow-params-inside-async-arrow-params copy/input.js b/packages/babel-parser/test/fixtures/es2017/async-functions/await-object-key-inside-arrow-params-inside-async-arrow-params copy/input.js
new file mode 100644
index 000000000000..72058aa6dd6b
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-object-key-inside-arrow-params-inside-async-arrow-params copy/input.js	
@@ -0,0 +1 @@
+async (a = ({ await: x }) => {}) => {};
diff --git a/packages/babel-parser/test/fixtures/es2017/async-functions/await-object-key-inside-arrow-params-inside-async-arrow-params copy/output.json b/packages/babel-parser/test/fixtures/es2017/async-functions/await-object-key-inside-arrow-params-inside-async-arrow-params copy/output.json
new file mode 100644
index 000000000000..0d5a5b2fa589
--- /dev/null
+++ b/packages/babel-parser/test/fixtures/es2017/async-functions/await-object-key-inside-arrow-params-inside-async-arrow-params copy/output.json	
@@ -0,0 +1,225 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 39,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 39
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 39,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 39
+      }
+    },
+    "sourceType": "script",
+    "interpreter": null,
+    "body": [
+      {
+        "type": "ExpressionStatement",
+        "start": 0,
+        "end": 39,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 39
+          }
+        },
+        "expression": {
+          "type": "ArrowFunctionExpression",
+          "start": 0,
+          "end": 38,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 0
+            },
+            "end": {
+              "line": 1,
+              "column": 38
+            }
+          },
+          "id": null,
+          "generator": false,
+          "async": true,
+          "params": [
+            {
+              "type": "AssignmentPattern",
+              "start": 7,
+              "end": 31,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 7
+                },
+                "end": {
+                  "line": 1,
+                  "column": 31
+                }
+              },
+              "left": {
+                "type": "Identifier",
+                "start": 7,
+                "end": 8,
+                "loc": {
+                  "start": {
+                    "line": 1,
+                    "column": 7
+                  },
+                  "end": {
+                    "line": 1,
+                    "column": 8
+                  },
+                  "identifierName": "a"
+                },
+                "name": "a"
+              },
+              "right": {
+                "type": "ArrowFunctionExpression",
+                "start": 11,
+                "end": 31,
+                "loc": {
+                  "start": {
+                    "line": 1,
+                    "column": 11
+                  },
+                  "end": {
+                    "line": 1,
+                    "column": 31
+                  }
+                },
+                "id": null,
+                "generator": false,
+                "async": false,
+                "params": [
+                  {
+                    "type": "ObjectPattern",
+                    "start": 12,
+                    "end": 24,
+                    "loc": {
+                      "start": {
+                        "line": 1,
+                        "column": 12
+                      },
+                      "end": {
+                        "line": 1,
+                        "column": 24
+                      }
+                    },
+                    "properties": [
+                      {
+                        "type": "ObjectProperty",
+                        "start": 14,
+                        "end": 22,
+                        "loc": {
+                          "start": {
+                            "line": 1,
+                            "column": 14
+                          },
+                          "end": {
+                            "line": 1,
+                            "column": 22
+                          }
+                        },
+                        "method": false,
+                        "key": {
+                          "type": "Identifier",
+                          "start": 14,
+                          "end": 19,
+                          "loc": {
+                            "start": {
+                              "line": 1,
+                              "column": 14
+                            },
+                            "end": {
+                              "line": 1,
+                              "column": 19
+                            },
+                            "identifierName": "await"
+                          },
+                          "name": "await"
+                        },
+                        "computed": false,
+                        "shorthand": false,
+                        "value": {
+                          "type": "Identifier",
+                          "start": 21,
+                          "end": 22,
+                          "loc": {
+                            "start": {
+                              "line": 1,
+                              "column": 21
+                            },
+                            "end": {
+                              "line": 1,
+                              "column": 22
+                            },
+                            "identifierName": "x"
+                          },
+                          "name": "x"
+                        }
+                      }
+                    ]
+                  }
+                ],
+                "body": {
+                  "type": "BlockStatement",
+                  "start": 29,
+                  "end": 31,
+                  "loc": {
+                    "start": {
+                      "line": 1,
+                      "column": 29
+                    },
+                    "end": {
+                      "line": 1,
+                      "column": 31
+                    }
+                  },
+                  "body": [],
+                  "directives": []
+                }
+              }
+            }
+          ],
+          "body": {
+            "type": "BlockStatement",
+            "start": 36,
+            "end": 38,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 36
+              },
+              "end": {
+                "line": 1,
+                "column": 38
+              }
+            },
+            "body": [],
+            "directives": []
+          }
+        }
+      }
+    ],
+    "directives": []
+  }
+}
\ No newline at end of file
diff --git a/scripts/tests/test262/test262_whitelist.txt b/scripts/tests/test262/test262_whitelist.txt
index 01c45f11a59d..a339397deb19 100644
--- a/scripts/tests/test262/test262_whitelist.txt
+++ b/scripts/tests/test262/test262_whitelist.txt
@@ -1,15 +1,5 @@
 language/expressions/assignment/destructuring/obj-prop-__proto__dup.js(default)
 language/expressions/assignment/destructuring/obj-prop-__proto__dup.js(strict mode)
-language/expressions/async-arrow-function/await-as-param-ident-nested-arrow-parameter-position.js(default)
-language/expressions/async-arrow-function/await-as-param-ident-nested-arrow-parameter-position.js(strict mode)
-language/expressions/async-arrow-function/await-as-param-nested-arrow-parameter-position.js(default)
-language/expressions/async-arrow-function/await-as-param-nested-arrow-parameter-position.js(strict mode)
-language/expressions/async-arrow-function/await-as-param-rest-nested-arrow-parameter-position.js(default)
-language/expressions/async-arrow-function/await-as-param-rest-nested-arrow-parameter-position.js(strict mode)
-language/expressions/async-arrow-function/early-errors-arrow-await-in-formals-default.js(default)
-language/expressions/async-arrow-function/early-errors-arrow-await-in-formals-default.js(strict mode)
-language/expressions/async-arrow-function/early-errors-arrow-await-in-formals.js(default)
-language/expressions/async-arrow-function/early-errors-arrow-await-in-formals.js(strict mode)
 language/expressions/class/elements/fields-duplicate-privatenames.js(default)
 language/expressions/class/elements/fields-duplicate-privatenames.js(strict mode)
 language/expressions/class/elements/private-methods/prod-private-method-initialize-order.js(default)