diff --git a/src/babel/traversal/path/resolution.js b/src/babel/traversal/path/resolution.js
index 88682620d7..70f8dfd4dc 100644
--- a/src/babel/traversal/path/resolution.js
+++ b/src/babel/traversal/path/resolution.js
@@ -1,13 +1,6 @@
 import type NodePath from "./index";
 import * as t from "../../types";
 
-const BOOLEAN_BINARY_OPERATORS = ["==", "===", "!=", "!==", ">", "<", ">=", "<=", "in", "instanceof"];
-const NUMBER_BINARY_OPERATORS  = ["-", "/", "*", "**", "&", "|", ">>", ">>>", "<<", "^"];
-
-const BOOLEAN_UNARY_OPERATORS = ["delete"];
-const NUMBER_UNARY_OPERATORS  = ["+", "-", "++", "--", "~"];
-const STRING_UNARY_OPERATORS  = ["typeof"];
-
 /**
  * Description
  */
@@ -131,6 +124,11 @@ export function _inferTypeAnnotation(force?: boolean): ?Object {
   var path = this.resolve();
 
   var node = path.node;
+
+  if (!node && path.key === "init" && path.parentPath.isVariableDeclarator()) {
+    return t.voidTypeAnnotation();
+  }
+
   if (!node) return;
 
   if (node.typeAnnotation) {
@@ -199,11 +197,11 @@ export function _inferTypeAnnotation(force?: boolean): ?Object {
 
     if (operator === "void") {
       return t.voidTypeAnnotation();
-    } else if (NUMBER_UNARY_OPERATORS.indexOf(operator) >= 0) {
+    } else if (t.NUMBER_UNARY_OPERATORS.indexOf(operator) >= 0) {
       return t.numberTypeAnnotation();
-    } else if (STRING_UNARY_OPERATORS.indexOf(operator) >= 0) {
+    } else if (t.STRING_UNARY_OPERATORS.indexOf(operator) >= 0) {
       return t.stringTypeAnnotation();
-    } else if (BOOLEAN_UNARY_OPERATORS.indexOf(operator) >= 0) {
+    } else if (t.BOOLEAN_UNARY_OPERATORS.indexOf(operator) >= 0) {
       return t.booleanTypeAnnotation();
     }
   }
@@ -211,9 +209,9 @@ export function _inferTypeAnnotation(force?: boolean): ?Object {
   if (path.isBinaryExpression()) {
     let operator = node.operator;
 
-    if (NUMBER_BINARY_OPERATORS.indexOf(operator) >= 0) {
+    if (t.NUMBER_BINARY_OPERATORS.indexOf(operator) >= 0) {
       return t.numberTypeAnnotation();
-    } else if (BOOLEAN_BINARY_OPERATORS.indexOf(operator) >= 0) {
+    } else if (t.BOOLEAN_BINARY_OPERATORS.indexOf(operator) >= 0) {
       return t.booleanTypeAnnotation();
     } else if (operator === "+") {
       var right = path.get("right").resolve();
@@ -260,15 +258,6 @@ export function _inferTypeAnnotation(force?: boolean): ?Object {
     }
   }
 
-  if (path.isUnaryExpression() && node.prefix) {
-    let operator = node.operator;
-    if (operator === "!") {
-      return t.booleanTypeAnnotation();
-    } else if (operator === "+" || operator === "-") {
-      return t.numberTypeAnnotation();
-    }
-  }
-
   if (path.isLiteral()) {
     var value = node.value;
     if (typeof value === "string") return t.stringTypeAnnotation();
diff --git a/src/babel/types/index.js b/src/babel/types/index.js
index fd1596aed4..b6fd35ec43 100644
--- a/src/babel/types/index.js
+++ b/src/babel/types/index.js
@@ -24,11 +24,17 @@ function registerType(type: string, skipAliasCheck?: boolean) {
   };
 }
 
-export var STATEMENT_OR_BLOCK_KEYS = ["consequent", "body", "alternate"];
-export var NATIVE_TYPE_NAMES       = ["Array", "ArrayBuffer", "Boolean", "DataView", "Date", "Error", "EvalError", "Float32Array", "Float64Array", "Function", "Int8Array", "Int16Array", "Int32Array", "Map", "Number", "Object", "Proxy", "Promise", "RangeError", "ReferenceError", "RegExp", "Set", "String", "Symbol", "SyntaxError", "TypeError", "Uint8Array", "Uint8ClampedArray", "Uint16Array", "Uint32Array", "URIError", "WeakMap", "WeakSet"];
-export var FLATTENABLE_KEYS        = ["body", "expressions"];
-export var FOR_INIT_KEYS           = ["left", "init"];
-export var COMMENT_KEYS            = ["leadingComments", "trailingComments"];
+export const STATEMENT_OR_BLOCK_KEYS = ["consequent", "body", "alternate"];
+export const FLATTENABLE_KEYS        = ["body", "expressions"];
+export const FOR_INIT_KEYS           = ["left", "init"];
+export const COMMENT_KEYS            = ["leadingComments", "trailingComments"];
+
+export const BOOLEAN_BINARY_OPERATORS = ["==", "===", "!=", "!==", ">", "<", ">=", "<=", "in", "instanceof"];
+export const NUMBER_BINARY_OPERATORS  = ["-", "/", "*", "**", "&", "|", ">>", ">>>", "<<", "^"];
+
+export const BOOLEAN_UNARY_OPERATORS = ["delete", "!"];
+export const NUMBER_UNARY_OPERATORS  = ["+", "-", "++", "--", "~"];
+export const STRING_UNARY_OPERATORS  = ["typeof"];
 
 export const VISITOR_KEYS = require("./visitor-keys");
 export const BUILDER_KEYS = require("./builder-keys");