diff --git a/Source/WebKit/NetworkProcess/cocoa/NetworkSessionCocoa.mm b/Source/WebKit/NetworkProcess/cocoa/NetworkSessionCocoa.mm
index 931e2adbba27..19999688fc3e 100644
--- a/Source/WebKit/NetworkProcess/cocoa/NetworkSessionCocoa.mm
+++ b/Source/WebKit/NetworkProcess/cocoa/NetworkSessionCocoa.mm
@@ -1403,7 +1403,8 @@ static void activateSessionCleanup(NetworkSessionCocoa& session, const NetworkSe
 
     NSURLSessionConfiguration *configuration = configurationForSessionID(m_sessionID, isParentProcessAFullWebBrowser(networkProcess));
 
-    m_blobRegistry.setFileDirectory(FileSystem::createTemporaryDirectory(@"BlobRegistryFiles"));
+    if (!m_sessionID.isEphemeral())
+        m_blobRegistry.setFileDirectory(FileSystem::createTemporaryDirectory(@"BlobRegistryFiles"));
 
     if (!!parameters.hstsStorageDirectory && !m_sessionID.isEphemeral()) {
         SandboxExtension::consumePermanently(parameters.hstsStorageDirectoryExtensionHandle);