diff --git a/src/context.c b/src/context.c
index 2312156..c8c11ae 100644
--- a/src/context.c
+++ b/src/context.c
@@ -589,21 +589,22 @@ apfl_ctx_new(struct apfl_allocator base_allocator)
         return NULL;
     }
 
-    apfl_gc_init(&ctx->gc, base_allocator, get_roots, ctx);
-
+    // It's important that we initialize all these before initializing the
+    // garbage collector, otherwise it might try to follow invalid pointers.
+    ctx->error_handler = NULL;
+    ctx->panic_callback = NULL;
+    ctx->panic_callback_data = NULL;
     ctx->toplevel_stack = apfl_stack_new();
     ctx->call_stack = call_stack_new();
+    ctx->globals = NULL;
+    ctx->iterative_runners = iterative_runners_list_new();
+
+    apfl_gc_init(&ctx->gc, base_allocator, get_roots, ctx);
 
     if ((ctx->globals = apfl_scope_new(&ctx->gc)) == NULL) {
         goto error;
     }
 
-    ctx->error_handler = NULL;
-    ctx->panic_callback = NULL;
-    ctx->panic_callback_data = NULL;
-
-    ctx->iterative_runners = iterative_runners_list_new();
-
     if (!init_globals(ctx)) {
         goto error;
     }
@@ -663,9 +664,34 @@ find_iterative_runner(apfl_ctx ctx, apfl_iterative_runner runner, size_t *index)
     return false;
 }
 
-bool
-apfl_ctx_register_iterative_runner(apfl_ctx ctx, apfl_iterative_runner runner)
+struct iterative_runner_tmproot_data {
+    struct gc *gc;
+    bool ok;
+};
+
+static void
+ctx_register_iterative_runner_tmproot(void *opaque, struct gc_object *object)
 {
+    struct iterative_runner_tmproot_data *data = opaque;
+    if (!data->ok) {
+        return;
+    }
+    data->ok = apfl_gc_tmproot_add(data->gc, object);
+}
+
+static bool
+ctx_register_iterative_runner_inner(apfl_ctx ctx, apfl_iterative_runner runner)
+{
+    struct iterative_runner_tmproot_data data = {
+        .gc = &ctx->gc,
+        .ok = true
+    };
+    apfl_iterative_runner_visit_gc_objects(runner, ctx_register_iterative_runner_tmproot, &data);
+
+    if (!data.ok) {
+        return false;
+    }
+
     if (find_iterative_runner(ctx, runner, NULL)) {
         return true;
     }
@@ -681,6 +707,15 @@ apfl_ctx_register_iterative_runner(apfl_ctx ctx, apfl_iterative_runner runner)
     );
 }
 
+bool
+apfl_ctx_register_iterative_runner(apfl_ctx ctx, apfl_iterative_runner runner)
+{
+    size_t tmproots = apfl_gc_tmproots_begin(&ctx->gc);
+    bool out = ctx_register_iterative_runner_inner(ctx, runner);
+    apfl_gc_tmproots_restore(&ctx->gc, tmproots);
+    return out;
+}
+
 void
 apfl_ctx_unregister_iterative_runner(apfl_ctx ctx, apfl_iterative_runner runner)
 {