diff --git a/py/mpstate.h b/py/mpstate.h
index 9bb87f0..5f6cf55 100644
--- a/py/mpstate.h
+++ b/py/mpstate.h
@@ -203,7 +203,7 @@
     size_t qstr_last_alloc;
     size_t qstr_last_used;
 
-    #if MICROPY_PY_THREAD
+    #if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
     // This is a global mutex used to make qstr interning thread-safe.
     mp_thread_mutex_t qstr_mutex;
     #endif
diff --git a/py/qstr.c b/py/qstr.c
index 29ffcae..940d09e 100644
--- a/py/qstr.c
+++ b/py/qstr.c
@@ -125,7 +125,7 @@
     MP_STATE_VM(last_pool) = (qstr_pool_t*)&CONST_POOL; // we won't modify the const_pool since it has no allocated room left
     MP_STATE_VM(qstr_last_chunk) = NULL;
 
-    #if MICROPY_PY_THREAD
+    #if MICROPY_PY_THREAD && !MICROPY_PY_THREAD_GIL
     mp_thread_mutex_init(&MP_STATE_VM(qstr_mutex));
     #endif
 }