diff --git a/.github/workflows/anvil-pr-impl.yml b/.github/workflows/anvil-pr-impl.yml
index b00fbf555..be362fdc1 100644
--- a/.github/workflows/anvil-pr-impl.yml
+++ b/.github/workflows/anvil-pr-impl.yml
@@ -316,7 +316,10 @@ jobs:
           publish_commit_statuses: ${{ inputs.publish_commit_statuses }}
           impact_mode: consume
         env:
-          BASE_REF: ${{ inputs.base_ref }}
+          # Diagnostic PR #765 targets PR #764's head. Diff mutation testing
+          # against #764's original base so this run can isolate the suspected
+          # Linux allocator mutant with streamed resource telemetry.
+          BASE_REF: ec1f6bc2d289f73202665952aa8a1492d13c40c4
 
   required-checks:
     # This display name is the repository-ruleset context. Keep it stable
diff --git a/crates/rallocator/Cargo.toml b/crates/rallocator/Cargo.toml
index 2c11127c5..69981704a 100644
--- a/crates/rallocator/Cargo.toml
+++ b/crates/rallocator/Cargo.toml
@@ -20,9 +20,6 @@ repository = "https://github.com/microsoft/oxidizer/tree/main/crates/rallocator"
 [target.'cfg(target_os = "linux")'.dependencies]
 libc.workspace = true
 
-[target.'cfg(target_os = "linux")'.dev-dependencies]
-mutants.workspace = true
-
 [target.'cfg(loom)'.dev-dependencies]
 loom.workspace = true
 
@@ -52,6 +49,7 @@ criterion.workspace = true
 hashbrown = { workspace = true, features = ["default-hasher"] }
 mimalloc.workspace = true
 multitude = { path = "../multitude", default-features = false, features = ["hashbrown"] }
+mutants.workspace = true
 performables = { path = "../performables", features = ["seismograph"] }
 seismograph = { path = "../seismograph", features = ["monitor"] }
 seismograph_runtime = { path = "../seismograph_runtime" }
diff --git a/crates/rallocator/src/allocator.rs b/crates/rallocator/src/allocator.rs
index bcbb3250c..6e285ec60 100644
--- a/crates/rallocator/src/allocator.rs
+++ b/crates/rallocator/src/allocator.rs
@@ -1944,6 +1944,7 @@ pub(crate) fn flush_thread_aggregate_batch() {
     unsafe { flush_aggregate_batch(state) };
 }
 
+#[cfg_attr(test, mutants::skip)] // Bit-clearing mutants create an unbounded iterator and OOM Linux runners.
 fn telemetry_used_slice_indices(bitmap: &[u64]) -> impl Iterator<Item = usize> + '_ {
     bitmap.iter().enumerate().flat_map(|(word_index, &word)| {
         let mut remaining = word;