1 files changed, 1 insertions, 1 deletions

diff --git a/src/WixToolset.Core.WindowsInstaller/ExtensibilityServices/WindowsInstallerBackendHelper.cs b/src/WixToolset.Core.WindowsInstaller/ExtensibilityServices/WindowsInstallerBackendHelper.cs
index ca1cd0e3..8305b5e6 100644
--- a/src/WixToolset.Core.WindowsInstaller/ExtensibilityServices/WindowsInstallerBackendHelper.cs
+++ b/src/WixToolset.Core.WindowsInstaller/ExtensibilityServices/WindowsInstallerBackendHelper.cs
@@ -37,7 +37,7 @@ namespace WixToolset.Core.WindowsInstaller.ExtensibilityServices
 
         public IResolvedDirectory CreateResolvedDirectory(string directoryParent, string name) => this.backendHelper.CreateResolvedDirectory(directoryParent, name);
 
-        public IEnumerable<ITrackedFile> ExtractEmbeddedFiles(IEnumerable<IExpectedExtractFile> embeddedFiles) => this.backendHelper.ExtractEmbeddedFiles(embeddedFiles);
+        public IReadOnlyList<ITrackedFile> ExtractEmbeddedFiles(IEnumerable<IExpectedExtractFile> embeddedFiles) => this.backendHelper.ExtractEmbeddedFiles(embeddedFiles);
 
         public string GenerateIdentifier(string prefix, params string[] args) => this.backendHelper.GenerateIdentifier(prefix, args);