diff --git a/benchmarks/mt-gcbench.c b/benchmarks/mt-gcbench.c
index 9d149c431..05ae887d0 100644
--- a/benchmarks/mt-gcbench.c
+++ b/benchmarks/mt-gcbench.c
@@ -205,14 +205,14 @@ static Node* make_tree(struct thread *t, int depth) {
 
 static void validate_tree(Node *tree, int depth) {
 #ifndef NDEBUG
-  ASSERT_EQ(tree->i, 0);
-  ASSERT_EQ(tree->j, depth);
+  GC_ASSERT_EQ(tree->i, 0);
+  GC_ASSERT_EQ(tree->j, depth);
   if (depth == 0) {
-    ASSERT(!tree->left);
-    ASSERT(!tree->right);
+    GC_ASSERT(!tree->left);
+    GC_ASSERT(!tree->right);
   } else {
-    ASSERT(tree->left);
-    ASSERT(tree->right);
+    GC_ASSERT(tree->left);
+    GC_ASSERT(tree->right);
     validate_tree(tree->left, depth - 1);
     validate_tree(tree->right, depth - 1);
   }
diff --git a/src/whippet.c b/src/whippet.c
index 4146eb88e..1ece0d3ff 100644
--- a/src/whippet.c
+++ b/src/whippet.c
@@ -1410,7 +1410,7 @@ static void mark_space_clear_remembered_set(struct mark_space *space) {
 
 void gc_write_barrier_extern(struct gc_ref obj, size_t obj_size,
                              struct gc_edge edge, struct gc_ref new_val) {
-  GC_ASSERT(size > gc_allocator_large_threshold());
+  GC_ASSERT(obj_size > gc_allocator_large_threshold());
   gc_object_set_remembered(obj);
 }