diff --git a/src/bootstrap/test.rs b/src/bootstrap/test.rs
index 92665c09f72aa..0c4816dc90458 100644
--- a/src/bootstrap/test.rs
+++ b/src/bootstrap/test.rs
@@ -755,10 +755,11 @@ default_test_with_compare_mode!(Ui {
     compare_mode: "nll"
 });
 
-default_test!(RunPass {
+default_test_with_compare_mode!(RunPass {
     path: "src/test/run-pass",
     mode: "run-pass",
-    suite: "run-pass"
+    suite: "run-pass",
+    compare_mode: "nll"
 });
 
 default_test!(CompileFail {
diff --git a/src/test/run-pass/project-defer-unification.rs b/src/test/run-pass/project-defer-unification.rs
index 901af09763b98..c4a3856bcbc2e 100644
--- a/src/test/run-pass/project-defer-unification.rs
+++ b/src/test/run-pass/project-defer-unification.rs
@@ -95,6 +95,10 @@ pub fn index_colors<Pix>(image: &ImageBuffer<Pix, Vec<u8>>)
                          -> ImageBuffer<Luma<u8>, Vec<u8>>
 where Pix: Pixel<Subpixel=u8> + 'static,
 {
+    // When NLL-enabled, `let mut` below is deemed unnecessary (due to
+    // the remaining code being unreachable); so ignore that lint.
+    #![allow(unused_mut)]
+
     let mut indices: ImageBuffer<_,Vec<_>> = loop { };
     for (pixel, idx) in image.pixels().zip(indices.pixels_mut()) {
         // failured occurred here ^^ because we were requiring that we