diff --git a/dom/apps/ImportExport.jsm b/dom/apps/ImportExport.jsm
index 34e05f25176..0c28d362c86 100644
--- a/dom/apps/ImportExport.jsm
+++ b/dom/apps/ImportExport.jsm
@@ -26,9 +26,6 @@ XPCOMUtils.defineLazyModuleGetter(this, "PermissionsInstaller",
 XPCOMUtils.defineLazyModuleGetter(this, "Task",
   "resource://gre/modules/Task.jsm");
 
-XPCOMUtils.defineLazyModuleGetter(this, "OS",
-  "resource://gre/modules/osfile.jsm");
-
 this.EXPORTED_SYMBOLS = ["ImportExport"];
 
 const kAppArchiveMimeType  = "application/openwebapp+zip";
@@ -228,12 +225,7 @@ this.ImportExport = {
     // |file| now points to application.zip, open it.
     let appZipReader = Cc["@mozilla.org/libjar/zip-reader;1"]
                          .createInstance(Ci.nsIZipReader);
-    try {
-      appZipReader.open(file);
-    } catch(e) {
-      throw "InvalidZip";
-    }
-
+    appZipReader.open(file);
     if (!appZipReader.hasEntry("manifest.webapp")) {
       throw "NoManifestFound";
     }
@@ -241,32 +233,10 @@ this.ImportExport = {
     return [readObjectFromZip(appZipReader, "manifest.webapp"), file];
   },
 
-  // Returns a promise that resolves to the temp file path.
-  _writeBlobToTempFile: function(aBlob) {
-    // Save the blob to a temp file.
-    let path;
-    return new Promise((aResolve, aReject) => {
-      let reader = Cc['@mozilla.org/files/filereader;1']
-                     .createInstance(Ci.nsIDOMFileReader);
-      reader.onloadend = () => {
-        path = OS.Path.join(OS.Constants.Path.tmpDir, "app-blob.zip");
-        OS.File.openUnique(path).then(file => {
-          path = file.path;
-          return OS.File.writeAtomic(path,
-                                     new Uint8Array(reader.result),
-                                     { tmpPath: path + ".tmp" })
-        })
-        .then(() => aResolve(path))
-        .catch(aReject);
-      }
-      reader.readAsArrayBuffer(aBlob);
-    });
-  },
-
   // Imports a blob, returning a Promise that resolves to
   // [manifestURL, manifest]
   // Possible errors are:
-  // NoBlobFound, InvalidZip, MissingMetadataFile, IncorrectVersion,
+  // NoBlobFound, UnsupportedBlobArchive, MissingMetadataFile, IncorrectVersion,
   // AppAlreadyInstalled, DontImportCertifiedApps, InvalidManifest,
   // InvalidPrivilegeLevel, InvalidOrigin, DuplicateOrigin
   import: Task.async(function*(aBlob) {
@@ -276,15 +246,15 @@ this.ImportExport = {
       throw "NoBlobFound";
     }
 
-    let isFileBlob = aBlob instanceof Ci.nsIDOMFile;
+    let isFile = aBlob instanceof Ci.nsIDOMFile;
+    if (!isFile) {
+      // XXX: TODO Store the blob on disk.
+      throw "UnsupportedBlobArchive";
+    }
+
     // We can't QI the DOMFile to nsIFile, so we need to create one.
     let zipFile = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
-    if (!isFileBlob) {
-      let path = yield this._writeBlobToTempFile(aBlob);
-      zipFile.initWithPath(path);
-    } else {
-      zipFile.initWithPath(aBlob.mozFullPath);
-    }
+    zipFile.initWithPath(aBlob.mozFullPath);
 
     debug("Importing from " + zipFile.path);
 
@@ -293,13 +263,8 @@ this.ImportExport = {
     let manifest;
     let zipReader = Cc["@mozilla.org/libjar/zip-reader;1"]
                       .createInstance(Ci.nsIZipReader);
+    zipReader.open(zipFile);
     try {
-      try {
-        zipReader.open(zipFile);
-      } catch(e) {
-        throw "InvalidZip";
-      }
-
       // Do some sanity checks on the metadata.json and manifest.webapp files.
       if (!zipReader.hasEntry("metadata.json")) {
         throw "MissingMetadataFile";
@@ -466,9 +431,6 @@ this.ImportExport = {
       throw e;
     } finally {
       zipReader.close();
-      if (!isFileBlob) {
-        zipFile.remove(false);
-      }
     }
 
     return [meta.manifestURL, manifest];
@@ -477,37 +439,31 @@ this.ImportExport = {
   // Extracts the manifest from a blob, returning a Promise that resolves to
   // the manifest
   // Possible errors are:
-  // NoBlobFound, InvalidZip, MissingMetadataFile.
+  // NoBlobFound, UnsupportedBlobArchive, MissingMetadataFile.
   extractManifest: Task.async(function*(aBlob) {
     // First, do we even have a blob?
     if (!aBlob || !aBlob instanceof Ci.nsIDOMBlob) {
       throw "NoBlobFound";
     }
 
-    let isFileBlob = aBlob instanceof Ci.nsIDOMFile;
-    // We can't QI the DOMFile to nsIFile, so we need to create one.
-    let zipFile = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
-    if (!isFileBlob) {
-      let path = yield this._writeBlobToTempFile(aBlob);
-      zipFile.initWithPath(path);
-    } else {
-      zipFile.initWithPath(aBlob.mozFullPath);
+    let isFile = aBlob instanceof Ci.nsIDOMFile;
+    if (!isFile) {
+      // XXX: TODO Store the blob on disk.
+      throw "UnsupportedBlobArchive";
     }
 
+    // We can't QI the DOMFile to nsIFile, so we need to create one.
+    let zipFile = Cc["@mozilla.org/file/local;1"].createInstance(Ci.nsIFile);
+    zipFile.initWithPath(aBlob.mozFullPath);
     debug("extractManifest from " + zipFile.path);
 
     // Do some sanity checks on the metadata.json and manifest.webapp files.
     let zipReader = Cc["@mozilla.org/libjar/zip-reader;1"]
                       .createInstance(Ci.nsIZipReader);
+    zipReader.open(zipFile);
 
     let manifest;
     try {
-      try {
-        zipReader.open(zipFile);
-      } catch(e) {
-        throw "InvalidZip";
-      }
-
       if (zipReader.hasEntry("manifest.webapp")) {
         manifest = readObjectFromZip(zipReader, "manifest.webapp");
         if (!manifest) {
@@ -528,9 +484,6 @@ this.ImportExport = {
       }
     } finally {
       zipReader.close();
-      if (!isFileBlob) {
-        zipFile.remove(false);
-      }
     }
 
     return manifest;
diff --git a/dom/apps/tests/test_import_export.html b/dom/apps/tests/test_import_export.html
index cd1739eaa7e..524eda94620 100644
--- a/dom/apps/tests/test_import_export.html
+++ b/dom/apps/tests/test_import_export.html
@@ -299,21 +299,6 @@ function runTest() {
   is(request.result, miniManifestURL, "Packaged App uninstalled.");
   navigator.mozApps.mgmt.onuninstall = null;
 
-
-  // Check that we support memory backed blobs.
-  // The blob here is not a valid app, but that's fine for this test.
-  let blob = new Blob(["This is a test blob."]);
-  navigator.mozApps.mgmt.import(blob)
-    .then(() => {
-      ok(false, "This is not an app!");
-      continueTest();
-    })
-    .catch(aError => {
-      is(aError.name, "InvalidZip", "Memory blob processed.");
-      continueTest();
-    });
-  yield undefined;
-
   // Check that we restored the app registry.
   request = navigator.mozApps.mgmt.getAll();
   request.onerror = cbError;