diff --git a/all-is-cubes/src/block/attributes.rs b/all-is-cubes/src/block/attributes.rs
index 152b478fe..f1384927e 100644
--- a/all-is-cubes/src/block/attributes.rs
+++ b/all-is-cubes/src/block/attributes.rs
@@ -137,6 +137,7 @@ impl BlockAttributes {
         Self::DEFAULT
     }
 
+    #[mutants::skip] // currently used only as an optimization, and hard to test usefully
     pub(crate) fn rotationally_symmetric(&self) -> bool {
         let Self {
             display_name: _,
diff --git a/all-is-cubes/src/space/light/queue.rs b/all-is-cubes/src/space/light/queue.rs
index c1906ca23..a54d4b622 100644
--- a/all-is-cubes/src/space/light/queue.rs
+++ b/all-is-cubes/src/space/light/queue.rs
@@ -211,6 +211,7 @@ impl LightUpdateQueue {
 
     /// Removes and returns the highest priority queue entry.
     #[inline]
+    #[mutants::skip] // if it fails to pop, causes hangs
     pub fn pop(&mut self) -> Option<LightUpdateRequest> {
         if let Some(sweep) = &mut self.sweep {
             if peek_priority(&self.queue).is_none_or(|p| self.sweep_priority > p) {
diff --git a/all-is-cubes/src/space/light/updater.rs b/all-is-cubes/src/space/light/updater.rs
index 09f04633d..b3829a47f 100644
--- a/all-is-cubes/src/space/light/updater.rs
+++ b/all-is-cubes/src/space/light/updater.rs
@@ -113,6 +113,7 @@ impl LightStorage {
         }
     }
 
+    #[mutants::skip] // lots of ways for this to still work when modified
     pub(crate) fn light_needs_update_in_region(&mut self, region: GridAab, priority: Priority) {
         let Some(region) = region.intersection_cubes(self.contents.bounds()) else {
             return;