diff --git a/oscars/src/collectors/mark_sweep/internals/gc_header.rs b/oscars/src/collectors/mark_sweep/internals/gc_header.rs
index c42cfa3..0b43c26 100644
--- a/oscars/src/collectors/mark_sweep/internals/gc_header.rs
+++ b/oscars/src/collectors/mark_sweep/internals/gc_header.rs
@@ -177,4 +177,14 @@ mod tests {
         assert!(!header.is_white(), "failed to toggle black");
         assert!(!header.is_grey(), "failed to toggle black");
     }
+
+    #[test]
+    #[should_panic(expected = "GcHeader root_count overflow")]
+    fn root_count_overflow_panics() {
+        let header = GcHeader::new_white();
+
+        for _ in 0..=u16::MAX {
+            header.inc_roots();
+        }
+    }
 }
diff --git a/oscars/src/collectors/mark_sweep/tests.rs b/oscars/src/collectors/mark_sweep/tests.rs
index 100feb6..ce54609 100644
--- a/oscars/src/collectors/mark_sweep/tests.rs
+++ b/oscars/src/collectors/mark_sweep/tests.rs
@@ -1,3 +1,6 @@
+#[cfg(feature = "std")]
+extern crate std;
+
 use crate::collectors::mark_sweep::MarkSweepGarbageCollector;
 use crate::{Finalize, Trace};