diff --git a/src/alloc/ArenaAlloc.cpp b/src/alloc/ArenaAlloc.cpp
index d7f794f3..dc80eb4e 100644
--- a/src/alloc/ArenaAlloc.cpp
+++ b/src/alloc/ArenaAlloc.cpp
@@ -390,8 +390,10 @@ namespace xo {
 
             /* word size for alignment */
             constexpr uint32_t c_bpw = sizeof(std::uintptr_t);
+            (void)c_bpw;
 
             std::uintptr_t free_u64 = reinterpret_cast<std::uintptr_t>(free_ptr_);
+            (void)free_u64;
 
             assert(free_u64 % c_bpw == 0ul);
 
diff --git a/src/alloc/GC.cpp b/src/alloc/GC.cpp
index dd17fd3b..f1c52d1b 100644
--- a/src/alloc/GC.cpp
+++ b/src/alloc/GC.cpp
@@ -551,7 +551,7 @@ namespace xo {
                 case generation_result::nursery:
                     if (is_before_checkpoint(parent)) {
                         log && log(xtag("act", "N1->N0 must mlog"));
-                        
+
                         // N1->N0, so must log
                         this->mutation_log_[role2int(role::to_space)]->push_back(MutationLogEntry(parent, lhs));
                         ++(this->gc_statistics_.n_logged_mutation_);
@@ -974,12 +974,14 @@ namespace xo {
 
                                 from_entry.fixup_parent_child_moved(child_to);
 
+#ifndef NDEBUG
                                 {
                                     // verify fixup was effective
                                     IObject * child_from2 = from_entry.child();
                                     assert(child_from2 == child_to);
                                 }
-                                
+#endif
+
 
                                 // P->C', loc(C') in {N1', T'}