diff --git a/crates/mdbook-driver/src/mdbook.rs b/crates/mdbook-driver/src/mdbook.rs
index e5dac902..03ebcb8c 100644
--- a/crates/mdbook-driver/src/mdbook.rs
+++ b/crates/mdbook-driver/src/mdbook.rs
@@ -263,11 +263,6 @@ impl MDBook {
             }
         }
 
-        // Index Preprocessor is disabled so that chapter paths
-        // continue to point to the actual markdown files.
-        self.preprocessors = determine_preprocessors(&self.config, &self.root)?;
-        self.preprocessors
-            .shift_remove_entry(IndexPreprocessor::NAME);
         let (book, _) = self.preprocess_book(&TestRenderer)?;
 
         let color_output = std::io::stderr().is_terminal();
diff --git a/tests/testsuite/preprocessor.rs b/tests/testsuite/preprocessor.rs
index 7aa02bd5..33c32078 100644
--- a/tests/testsuite/preprocessor.rs
+++ b/tests/testsuite/preprocessor.rs
@@ -54,8 +54,8 @@ fn test_with_custom_preprocessor() {
     book.test(vec![]).unwrap();
 
     let inner = spy.lock().unwrap();
-    assert_eq!(inner.run_count, 0);
-    assert_eq!(inner.rendered_with, Vec::<String>::new());
+    assert_eq!(inner.run_count, 1);
+    assert_eq!(inner.rendered_with, ["test"]);
 }
 
 // No-op preprocessor works.