diff --git a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/LocalDiskRepositoryTestCase.java b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/LocalDiskRepositoryTestCase.java
index 568fcdcd0..dd143826e 100644
--- a/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/LocalDiskRepositoryTestCase.java
+++ b/org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/LocalDiskRepositoryTestCase.java
@@ -119,6 +119,11 @@ public abstract class LocalDiskRepositoryTestCase extends TestCase {
 				shutdownHook = new Thread() {
 					@Override
 					public void run() {
+						// On windows accidentally open files or memory
+						// mapped regions may prevent files from being deleted.
+						// Suggesting a GC increases the likelihood that our
+						// test repositories actually get removed after the
+						// tests, even in the case of failure.
 						System.gc();
 						recursiveDelete("SHUTDOWN", trash, false, false);
 					}