diff --git a/src/Tests/ComparisonTests.cs b/src/Tests/ComparisonTests.cs
index 883a98ee..1377d323 100644
--- a/src/Tests/ComparisonTests.cs
+++ b/src/Tests/ComparisonTests.cs
@@ -20,6 +20,9 @@ public void Initialize()
 
         private static void CompareStreams(FileStream expectedStream, MemoryStream outputStream)
         {
+            Assert.IsNotNull(outputStream);
+            Assert.AreNotEqual(0, outputStream.Length);
+
 #if NETCOREAPP3_0_OR_GREATER
             // the expected images are for Windows
             if (!RuntimeInformation.IsOSPlatform(OSPlatform.Windows))