diff --git a/atom/browser/api/atom_api_web_contents.cc b/atom/browser/api/atom_api_web_contents.cc
index 77fbf9f1de8a..d22f7aab61fd 100644
--- a/atom/browser/api/atom_api_web_contents.cc
+++ b/atom/browser/api/atom_api_web_contents.cc
@@ -165,9 +165,12 @@ WebContents::WebContents(v8::Isolate* isolate,
   std::string partition;
   mate::Handle<api::Session> session;
   if (options.Get("session", &session)) {
-  } else if (options.Get("partition", &partition)) {
+  } else if (options.Get("partition", &partition) && !partition.empty()) {
     bool in_memory = true;
-    options.Get("inMemory", &in_memory);
+    if (base::StartsWith(partition, "persist:", base::CompareCase::SENSITIVE)) {
+      in_memory = false;
+      partition = partition.substr(8);
+    }
     session = Session::FromPartition(isolate, partition, in_memory);
   } else {
     // Use the default session if not specified.
diff --git a/atom/browser/lib/guest-view-manager.coffee b/atom/browser/lib/guest-view-manager.coffee
index c7ec439f96f0..1c05b65b2dc0 100644
--- a/atom/browser/lib/guest-view-manager.coffee
+++ b/atom/browser/lib/guest-view-manager.coffee
@@ -38,21 +38,12 @@ moveLastToFirst = (list) ->
 getNextInstanceId = (webContents) ->
   ++nextInstanceId
 
-# Parse the partition string.
-parsePartition = (partition) ->
-  return ['', false] unless partition
-  if partition.startsWith 'persist:'
-    [partition.substr('persist:'.length), false]
-  else
-    [partition, true]
-
 # Create a new guest instance.
 createGuest = (embedder, params) ->
   webViewManager ?= process.atomBinding 'web_view_manager'
 
   id = getNextInstanceId embedder
-  [partition, inMemory] = parsePartition params.partition
-  guest = webContents.create {isGuest: true, partition, inMemory, embedder}
+  guest = webContents.create {isGuest: true, partition: params.partition, embedder}
   guestInstances[id] = {guest, embedder}
 
   # Destroy guest when the embedder is gone or navigated.