diff --git a/lib/core.ps1 b/lib/core.ps1
index b0e833c74b..bf281ec3c6 100644
--- a/lib/core.ps1
+++ b/lib/core.ps1
@@ -16,8 +16,8 @@ function Get-PESubsystem($filePath) {
     } catch {
         return -1
     } finally {
-        $binaryReader.Close()
-        $fileStream.Close()
+        if ($null -ne $binaryReader) { $binaryReader.Close() }
+        if ($null -ne $fileStream) { $fileStream.Close() }
     }
 }