diff --git a/package.json b/package.json
index 7314b7b8..95082994 100644
--- a/package.json
+++ b/package.json
@@ -45,7 +45,7 @@
     "scratch-audio": "^0.1.0-prerelease.0",
     "scratch-blocks": "^0.1.0-prerelease.0",
     "scratch-render": "^0.1.0-prerelease.0",
-    "scratch-storage": "^0.1.0",
+    "scratch-storage": "^0.2.0",
     "script-loader": "0.7.0",
     "socket.io-client": "1.7.3",
     "stats.js": "^0.17.0",
diff --git a/src/import/load-costume.js b/src/import/load-costume.js
index a9323398..54962ea1 100644
--- a/src/import/load-costume.js
+++ b/src/import/load-costume.js
@@ -1,3 +1,4 @@
+const StringUtil = require('../util/string-util');
 const log = require('../util/log');
 
 /**
@@ -19,17 +20,17 @@ const loadCostume = function (md5ext, costume, runtime) {
     }
 
     const AssetType = runtime.storage.AssetType;
-    const idParts = md5ext.split('.');
+    const idParts = StringUtil.splitFirst(md5ext, '.');
     const md5 = idParts[0];
-    const ext = idParts[1].toUpperCase();
-    const assetType = (ext === 'SVG') ? AssetType.ImageVector : AssetType.ImageBitmap;
+    const ext = idParts[1].toLowerCase();
+    const assetType = (ext === 'svg') ? AssetType.ImageVector : AssetType.ImageBitmap;
 
     const rotationCenter = [
         costume.rotationCenterX / costume.bitmapResolution,
         costume.rotationCenterY / costume.bitmapResolution
     ];
 
-    let promise = runtime.storage.load(assetType, md5).then(costumeAsset => {
+    let promise = runtime.storage.load(assetType, md5, ext).then(costumeAsset => {
         costume.assetId = costumeAsset.assetId;
         costume.assetType = assetType;
         return costumeAsset;
diff --git a/src/import/load-sound.js b/src/import/load-sound.js
index a308e151..80b59598 100644
--- a/src/import/load-sound.js
+++ b/src/import/load-sound.js
@@ -1,3 +1,4 @@
+const StringUtil = require('../util/string-util');
 const log = require('../util/log');
 
 /**
@@ -17,9 +18,10 @@ const loadSound = function (sound, runtime) {
         log.error('No audio engine present; cannot load sound asset: ', sound.md5);
         return Promise.resolve(sound);
     }
-    const idParts = sound.md5.split('.');
+    const idParts = StringUtil.splitFirst(sound.md5, '.');
     const md5 = idParts[0];
-    return runtime.storage.load(runtime.storage.AssetType.Sound, md5)
+    const ext = idParts[1].toLowerCase();
+    return runtime.storage.load(runtime.storage.AssetType.Sound, md5, ext)
         .then(soundAsset => {
             sound.assetId = soundAsset.assetId;
             sound.assetType = runtime.storage.AssetType.Sound;
diff --git a/src/playground/playground.js b/src/playground/playground.js
index c1b655a5..814bfb62 100644
--- a/src/playground/playground.js
+++ b/src/playground/playground.js
@@ -34,7 +34,7 @@ const getAssetUrl = function (asset) {
         'internalapi/asset/',
         asset.assetId,
         '.',
-        asset.assetType.runtimeFormat,
+        asset.dataFormat,
         '/get/'
     ];
     return assetUrlParts.join('');
diff --git a/src/serialization/sb3.js b/src/serialization/sb3.js
index 161dbd2f..816b1af1 100644
--- a/src/serialization/sb3.js
+++ b/src/serialization/sb3.js
@@ -75,7 +75,7 @@ const parseScratchObject = function (object, runtime) {
             rotationCenterX: costumeSource.rotationCenterX,
             rotationCenterY: costumeSource.rotationCenterY
         };
-        const costumeMd5 = `${costumeSource.assetId}.${costumeSource.assetType.runtimeFormat}`;
+        const costumeMd5 = `${costumeSource.assetId}.${costumeSource.dataFormat}`;
         return loadCostume(costumeMd5, costume, runtime);
     });
     // Sounds from JSON
diff --git a/src/util/string-util.js b/src/util/string-util.js
index 0ee71254..48dde027 100644
--- a/src/util/string-util.js
+++ b/src/util/string-util.js
@@ -12,6 +12,30 @@ class StringUtil {
         while (existingNames.indexOf(name + i) >= 0) i++;
         return name + i;
     }
+
+    /**
+     * Split a string on the first occurrence of a split character.
+     * @param {string} text - the string to split.
+     * @param {string} separator - split the text on this character.
+     * @returns {[string, string]} - the two parts of the split string, or [text, null] if no split character found.
+     * @example
+     * // returns ['foo', 'tar.gz']
+     * splitFirst('foo.tar.gz', '.');
+     * @example
+     * // returns ['foo', null]
+     * splitFirst('foo', '.');
+     * @example
+     * // returns ['foo', '']
+     * splitFirst('foo.', '.');
+     */
+    static splitFirst (text, separator) {
+        const index = text.indexOf(separator);
+        if (index >= 0) {
+            return [text.substring(0, index), text.substring(index + 1)];
+        } else {
+            return [text, null];
+        }
+    }
 }
 
 module.exports = StringUtil;
diff --git a/test/fixtures/attach-test-storage.js b/test/fixtures/attach-test-storage.js
index 3e75f596..bb0cc3a0 100644
--- a/test/fixtures/attach-test-storage.js
+++ b/test/fixtures/attach-test-storage.js
@@ -26,7 +26,7 @@ const getAssetUrl = function (asset) {
         'internalapi/asset/',
         asset.assetId,
         '.',
-        asset.assetType.runtimeFormat,
+        asset.dataFormat,
         '/get/'
     ];
     return assetUrlParts.join('');
diff --git a/test/unit/util_string.js b/test/unit/util_string.js
index 74133625..aca20f9a 100644
--- a/test/unit/util_string.js
+++ b/test/unit/util_string.js
@@ -1,6 +1,14 @@
 const test = require('tap').test;
 const StringUtil = require('../../src/util/string-util');
 
+test('splitFirst', t => {
+    t.deepEqual(StringUtil.splitFirst('asdf.1234', '.'), ['asdf', '1234']);
+    t.deepEqual(StringUtil.splitFirst('asdf.', '.'), ['asdf', '']);
+    t.deepEqual(StringUtil.splitFirst('.1234', '.'), ['', '1234']);
+    t.deepEqual(StringUtil.splitFirst('foo', '.'), ['foo', null]);
+    t.end();
+});
+
 test('withoutTrailingDigits', t => {
     t.strictEqual(StringUtil.withoutTrailingDigits('boeing747'), 'boeing');
     t.strictEqual(StringUtil.withoutTrailingDigits('boeing747 '), 'boeing747 ');