diff --git a/src/main/java/org/jenkinsci/plugins/artifactdiff/ArtifactDifference.java b/src/main/java/org/jenkinsci/plugins/artifactdiff/ArtifactDifference.java
index 28a315b..586ca7d 100644
--- a/src/main/java/org/jenkinsci/plugins/artifactdiff/ArtifactDifference.java
+++ b/src/main/java/org/jenkinsci/plugins/artifactdiff/ArtifactDifference.java
@@ -104,7 +104,7 @@ public String getFilename(
 
         final String artifactPath = artifact.getFile().getCanonicalPath();
 
-        assert artifactPath.startsWith(prefix);
+        assert artifact.getFile().getCanonicalFile().toPath().startsWith(prefix);
 
         return artifactPath.substring(prefix.length());
     }