diff --git a/act/container/docker_run.go b/act/container/docker_run.go
index 79e35d1c..3c6fcff4 100644
--- a/act/container/docker_run.go
+++ b/act/container/docker_run.go
@@ -400,7 +400,7 @@ func (cr *containerReference) copyDir(dstPath string, srcPath string) common.Exe
 			}
 
 			// update the name to correctly reflect the desired destination when untaring
-			header.Name = sansPrefix
+			header.Name = filepath.ToSlash(sansPrefix)
 			header.Mode = int64(fi.Mode())
 			header.ModTime = fi.ModTime()