diff --git a/include/cubescript/cubescript.hh b/include/cubescript/cubescript.hh
index de2f2b0..bc16a37 100644
--- a/include/cubescript/cubescript.hh
+++ b/include/cubescript/cubescript.hh
@@ -560,7 +560,6 @@ struct LIBCUBESCRIPT_EXPORT state {
     void swap(state &s) {
         std::swap(p_tstate, s.p_tstate);
         std::swap(identflags, s.identflags);
-        std::swap(p_owner, s.p_owner);
     }
 
     state new_thread();
@@ -733,8 +732,6 @@ private:
     ident *add_ident(ident *id, ident_impl *impl);
 
     void *alloc(void *ptr, size_t olds, size_t news);
-
-    bool p_owner = false;
 };
 
 struct stack_state_node {
diff --git a/src/cs_state.cc b/src/cs_state.cc
index 2fcdc8e..ef234de 100644
--- a/src/cs_state.cc
+++ b/src/cs_state.cc
@@ -71,7 +71,7 @@ state::state(alloc_func func, void *data) {
 
     p_tstate->pstate = this;
     p_tstate->istate = statep;
-    p_owner = true;
+    p_tstate->owner = true;
 
     for (int i = 0; i < MAX_ARGUMENTS; ++i) {
         char buf[32];
@@ -188,7 +188,7 @@ LIBCUBESCRIPT_EXPORT state::~state() {
 }
 
 LIBCUBESCRIPT_EXPORT void state::destroy() {
-    if (!p_tstate || !p_owner) {
+    if (!p_tstate || !p_tstate->owner) {
         return;
     }
     auto *sp = p_tstate->istate;
@@ -205,9 +205,7 @@ LIBCUBESCRIPT_EXPORT void state::destroy() {
     sp->destroy(sp);
 }
 
-state::state(internal_state *s):
-    p_owner{false}
-{
+state::state(internal_state *s) {
     p_tstate = s->create<thread_state>(s);
     p_tstate->istate = s;
 }
diff --git a/src/cs_thread.hh b/src/cs_thread.hh
index b2add06..8fbe3f4 100644
--- a/src/cs_thread.hh
+++ b/src/cs_thread.hh
@@ -29,6 +29,8 @@ struct thread_state {
     hook_func call_hook{};
     /* loop nesting level */
     int loop_level = 0;
+    /* whether we own the internal state (i.e. not a side thread */
+    bool owner = false;
 
     thread_state(internal_state *cs);