diff --git a/package.json b/package.json
index 7830dbe1..34dde2fa 100644
--- a/package.json
+++ b/package.json
@@ -47,9 +47,9 @@
   "scripts": {
     "build": "gulp",
     "clean": "rm -rf dist/npm && rm -rf build/flow",
-    "typecheck": "babel -i runtime --blacklist flow -d build/flow/ src/ && flow",
-    "compile": "babel -i runtime -d dist/npm/ src/",
-    "compile-with-source-maps": "babel -i runtime -s -t -d dist/npm/ src/",
+    "typecheck": "babel --optional runtime --blacklist flow -d build/flow/ src/ && flow",
+    "compile": "babel --optional runtime -d dist/npm/ src/ && cp -r src/api/common/schemas/ dist/npm/api/common/schemas/",
+    "compile-with-source-maps": "babel --optional runtime -s -t -d dist/npm/ src/",
     "prepublish": "npm run clean && npm run compile",
     "test": "istanbul test _mocha",
     "coveralls": "cat ./coverage/lcov.info | coveralls",
diff --git a/scripts/verify_ledger_json.js b/scripts/verify_ledger_json.js
index f902d588..a2139b25 100755
--- a/scripts/verify_ledger_json.js
+++ b/scripts/verify_ledger_json.js
@@ -3,7 +3,7 @@
 
 var fs = require('fs');
 var Amount = require('../dist/npm').Amount;
-var Ledger = require('../dist/npm/ledger').Ledger;
+var Ledger = require('../dist/npm').Ledger;
 
 function parse_options(from, flags) {
   var argv = from.slice(),
diff --git a/src/api/common/schema-validator.js b/src/api/common/schema-validator.js
index 8f989f71..4dabcbea 100644
--- a/src/api/common/schema-validator.js
+++ b/src/api/common/schema-validator.js
@@ -24,8 +24,12 @@ function loadSchema(filepath) {
   }
 }
 
+function endsWith(str, suffix) {
+  return str.indexOf(suffix, str.length - suffix.length) !== -1;
+}
+
 function loadSchemas(dir) {
-  const filenames = fs.readdirSync(dir).filter(name => name.endsWith('.json'));
+  const filenames = fs.readdirSync(dir).filter(name => endsWith(name, '.json'));
   const schemas = filenames.map(name => loadSchema(path.join(dir, name)));
   return _.indexBy(schemas, 'title');
 }
diff --git a/src/api/transaction/utils.js b/src/api/transaction/utils.js
index 7823cbeb..11f753c7 100644
--- a/src/api/transaction/utils.js
+++ b/src/api/transaction/utils.js
@@ -39,7 +39,7 @@ function getFeeDrops(remote) {
   return remote.feeTx(feeUnits).to_text();
 }
 
-/*:: type Callback = (err: typeof Error, data: {tx_json: any}) => void */
+/*:: type Callback = (err: ?(typeof Error), data: {tx_json: any}) => void */
 function createTxJSON(transaction: any, remote: any,
     instructions: any, callback: Callback): void {
   common.validate.instructions(instructions);