diff --git a/src/AppInstallerCommonCore/FileCache.cpp b/src/AppInstallerCommonCore/FileCache.cpp
index 4038baa3ab..1594445d44 100644
--- a/src/AppInstallerCommonCore/FileCache.cpp
+++ b/src/AppInstallerCommonCore/FileCache.cpp
@@ -210,8 +210,11 @@ namespace AppInstaller::Caching
         return result;
     }
 
-    std::unique_ptr<std::stringstream> FileCache::GetUpstreamFile(const std::string& relativePath, const Utility::SHA256::HashBuffer& expectedHash) const
+    std::unique_ptr<std::stringstream> FileCache::GetUpstreamFile(std::string relativePath, const Utility::SHA256::HashBuffer& expectedHash) const
     {
+        // Replace backslashes with forward slashes for HTTP requests (since local can handle them).
+        Utility::FindAndReplace(relativePath, "\\", "/");
+
         std::exception_ptr firstException;
 
         for (const auto& upstream : m_sources)
diff --git a/src/AppInstallerCommonCore/Public/winget/FileCache.h b/src/AppInstallerCommonCore/Public/winget/FileCache.h
index 1bea547d56..59d1826f3b 100644
--- a/src/AppInstallerCommonCore/Public/winget/FileCache.h
+++ b/src/AppInstallerCommonCore/Public/winget/FileCache.h
@@ -53,7 +53,7 @@ namespace AppInstaller::Caching
     private:
         // Gets a stream containing the contents of the requested file from an upstream source.
         // The hash must match for this function to return successfully.
-        std::unique_ptr<std::stringstream> GetUpstreamFile(const std::string& relativePath, const Utility::SHA256::HashBuffer& expectedHash) const;
+        std::unique_ptr<std::stringstream> GetUpstreamFile(std::string relativePath, const Utility::SHA256::HashBuffer& expectedHash) const;
 
         Details m_details;
         std::vector<std::string> m_sources;