diff --git a/.eslintrc b/.eslintrc
index 3a11e64e89..3c50bc0560 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -2,7 +2,9 @@
   "parser": "babel-eslint",
 
   "plugins": [
-    "babel"
+    "babel",
+    "flowtype",
+    "flow-vars"
   ],
 
   "env": {
@@ -44,6 +46,11 @@
     "array-bracket-spacing": 0,
     "generator-star-spacing": 0,
 
+    "flowtype/space-after-type-colon": [2, "always"],
+    "flowtype/space-before-type-colon": [2, "never"],
+    "flow-vars/define-flow-type": 2,
+    "flow-vars/use-flow-type": 2,
+
     "arrow-spacing": 2,
     "block-scoped-var": 0,
     "brace-style": [2, "1tbs", {"allowSingleLine": true}],
@@ -155,7 +162,7 @@
     "no-return-assign": 2,
     "no-script-url": 2,
     "no-self-compare": 0,
-    "no-sequences": 2,
+    "no-sequences": 0,
     "no-shadow": 2,
     "no-shadow-restricted-names": 2,
     "no-spaced-func": 2,
diff --git a/package.json b/package.json
index 166a38448b..cd9417dbde 100644
--- a/package.json
+++ b/package.json
@@ -38,23 +38,25 @@
     "babel-runtime": ">=6.0.0"
   },
   "devDependencies": {
-    "babel-cli": "6.6.5",
-    "babel-eslint": "6.0.2",
-    "babel-plugin-syntax-async-functions": "6.5.0",
-    "babel-plugin-transform-class-properties": "6.6.0",
-    "babel-plugin-transform-flow-strip-types": "6.7.0",
-    "babel-plugin-transform-object-rest-spread": "6.6.5",
-    "babel-plugin-transform-regenerator": "6.6.5",
-    "babel-plugin-transform-runtime": "6.6.0",
+    "babel-cli": "6.9.0",
+    "babel-eslint": "6.0.4",
+    "babel-plugin-syntax-async-functions": "6.8.0",
+    "babel-plugin-transform-class-properties": "6.9.1",
+    "babel-plugin-transform-flow-strip-types": "6.8.0",
+    "babel-plugin-transform-object-rest-spread": "6.8.0",
+    "babel-plugin-transform-regenerator": "6.9.0",
+    "babel-plugin-transform-runtime": "6.9.0",
     "babel-preset-es2015": "6.6.0",
     "chai": "3.5.0",
     "chai-subset": "1.2.2",
     "coveralls": "2.11.9",
-    "eslint": "2.7.0",
+    "eslint": "2.11.1",
     "eslint-plugin-babel": "3.2.0",
-    "flow-bin": "0.22.1",
+    "eslint-plugin-flow-vars": "^0.4.0",
+    "eslint-plugin-flowtype": "2.2.7",
+    "flow-bin": "0.26.0",
     "isparta": "4.0.0",
-    "mocha": "2.4.5",
+    "mocha": "2.5.3",
     "sane": "1.3.4"
   }
 }
diff --git a/src/language/lexer.js b/src/language/lexer.js
index c3d783435e..d325b0ab65 100644
--- a/src/language/lexer.js
+++ b/src/language/lexer.js
@@ -193,22 +193,19 @@ function readToken(source: Source, fromPosition: number): Token {
     case 124: return makeToken(TokenKind.PIPE, position, position + 1);
     // }
     case 125: return makeToken(TokenKind.BRACE_R, position, position + 1);
-    // A-Z
+    // A-Z _ a-z
     case 65: case 66: case 67: case 68: case 69: case 70: case 71: case 72:
     case 73: case 74: case 75: case 76: case 77: case 78: case 79: case 80:
     case 81: case 82: case 83: case 84: case 85: case 86: case 87: case 88:
     case 89: case 90:
-    // _
     case 95:
-    // a-z
     case 97: case 98: case 99: case 100: case 101: case 102: case 103: case 104:
     case 105: case 106: case 107: case 108: case 109: case 110: case 111:
     case 112: case 113: case 114: case 115: case 116: case 117: case 118:
     case 119: case 120: case 121: case 122:
       return readName(source, position);
-    // -
+    // - 0-9
     case 45:
-    // 0-9
     case 48: case 49: case 50: case 51: case 52:
     case 53: case 54: case 55: case 56: case 57:
       return readNumber(source, position, code);
diff --git a/src/language/parser.js b/src/language/parser.js
index 11faabb4b0..e1fa423a1b 100644
--- a/src/language/parser.js
+++ b/src/language/parser.js
@@ -204,10 +204,11 @@ function parseDefinition(parser: Parser): Definition {
 
   if (peek(parser, TokenKind.NAME)) {
     switch (parser.token.value) {
+      // Note: subscription is an experimental non-spec addition.
       case 'query':
       case 'mutation':
-      // Note: subscription is an experimental non-spec addition.
-      case 'subscription': return parseOperationDefinition(parser);
+      case 'subscription':
+        return parseOperationDefinition(parser);
 
       case 'fragment': return parseFragmentDefinition(parser);