diff --git a/js/src/gc/GCRuntime.h b/js/src/gc/GCRuntime.h
index 872e649fa8..638bd18c77 100644
--- a/js/src/gc/GCRuntime.h
+++ b/js/src/gc/GCRuntime.h
@@ -977,8 +977,6 @@ class GCRuntime
     void releaseRelocatedArenasWithoutUnlocking(Arena* arenaList, const AutoLockGC& lock);
     void finishCollection(JS::gcreason::Reason reason);
 
-    void finishMarkingValidation();
-
 #ifdef DEBUG
     void checkForCompartmentMismatches();
 #endif
diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
index 6fcb72b70a..04aaeba683 100644
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -3885,11 +3885,6 @@ GCRuntime::markAllGrayReferences(gcstats::Phase phase)
     markGrayReferences<GCZonesIter, GCCompartmentsIter>(phase);
 }
 
-void
-GCRuntime::finishMarkingValidation()
-{
-}
-
 static void
 DropStringWrappers(JSRuntime* rt)
 {
@@ -4994,8 +4989,6 @@ GCRuntime::endSweepPhase(bool destroyingRuntime, AutoLockForExclusiveAccess& loc
             rt->setGCGrayBitsValid(true);
     }
 
-    finishMarkingValidation();
-
 #ifdef DEBUG
     for (ZonesIter zone(rt, WithAtoms); !zone.done(); zone.next()) {
         for (auto i : AllAllocKinds()) {